Best Filament for the Original Prusa MK4 (2026)

Quick picks

These are defaults by need, not a ranking.

Who this page is for

This page is for owners of an Original Prusa MK4 who want to know which spools suit their printer before buying. If you own an MK4S, or upgraded your MK4 to one, see our CORE One and MK4S filament page instead. For nozzles and build plates that fit the MK4, see the MK4 printer page. Every spool here is 1.75 mm.

The table is grouped by job, not ranked. The ASA and ABS spools are for an enclosed MK4 only. The last two spools need the wear-resistant nozzle listed just above them.

What can the MK4 print, per Prusa?

Basics. Prusa's MK4 handbook (v1.03) lists a 250 × 210 × 220 mm build volume, a 0.4 mm installed nozzle and 1.75 mm filament. It says the MK4 "is compatible with almost all filaments available," and Prusa's 2023 launch post lists "Any thermoplastic including Nylon and Polycarbonate." That's what the hardware can reach. It doesn't mean every material prints easily in an open room, and Prusa's material guides add conditions, covered below.

Temperatures. Prusa's 2023 launch post lists the MK4's maximum hotend and heatbed temperatures as "300 °C / 120 °C." Prusa's MK4 product page now redirects to the MK4S, whose specifications list 290 °C and 120 °C. Prusa's current pages don't give a separate figure for the MK4, so we've used the lower 290 °C. Every spool on this page tops out well below either figure.

Open frame. The MK4 has no enclosure. Prusa's launch post says that because the MK4 has the same dimensions as the MK3S+, "it's fully compatible with the Original Prusa Enclosure." The current Enclosure page is titled "Original Prusa MK4/S Enclosure" and says it houses "your Original Prusa i3 MK3S+ or MK4." Prusa describes it as "Passive, heating provided only by the 3D printer's heatbed," with an optional HEPA filtration add-on. Prusa's MK4S comparison table lists a 45 °C maximum chamber temperature in the Enclosure. It isn't in our catalog, but it's the first enclosure to consider.

Print sheet. The handbook says "The Original Prusa MK4 comes standard with a double-sided smooth PEI print sheet." Prusa's launch FAQ says the MK4 takes the same smooth PEI, satin, textured (powder-coated) and PA Nylon sheets as the MK3. This matters for PETG, TPU, ASA and ABS, as each section below explains.

Heat in use. Prusa's PLA guide says PLA "gets soft and deforms at temperatures over 60 °C." Its PETG guide says PETG parts are suitable for interior and most exterior use "with temperatures below 80 °C." The handbook says ASA prints won't deform "up to temperatures around 100 °C." Our PLA vs ASA guide covers that trade-off.

How the MK4 differs from the MK4S

Prusa's MK4-to-MK4S upgrade page lists what the MK4S adds "Compared to the Original Prusa MK4." The two changes that matter for filament are these:

• Cooling. The MK4S has a "New high-performance 360° cooling system" with a turbine fan and a redesigned shroud. Prusa's MK4S announcement says "the cooling on the MK4 was already very good," and that the new cooling helps with steep overhangs, and with flexible filaments where supports are hard to remove. It also mentions better surface quality "especially on materials like PETG."
• Nozzle. The MK4S comes with a high-flow brass nozzle based on CHT technology. Prusa's upgrade page says it delivers "between 50 to 114% improved flow rate depending on the material and nozzle diameter" compared with the MK4's stock nozzle. The MK4 uses a regular brass nozzle, so it is no better suited to abrasive filament than the MK4S.

Prusa doesn't present either change as adding or removing materials. Its material guides are marked as relevant for the "MK4 family" as a group, and its ASA and ABS enclosure advice applies to both printers. Prusa sells an MK4-to-MK4S upgrade kit. It includes the CHT nozzle, the 360° fan and shroud, Nextruder parts, and a Wi-Fi board and NFC antenna, and Prusa says there are two versions depending on which xLCD your MK4 has. An upgraded MK4 counts as an MK4S, so use our CORE One and MK4S page after the upgrade.

Can the MK4 print carbon fiber on the stock nozzle?

Prusa's Nextruder nozzle guide says "The Prusa FFF printers are equipped with a brass nozzle," and that brass "tends to wear too quickly" with abrasive filaments. It adds that "Most of the abrasive materials are composites and plastics with additives." Its nozzle-size table marks wood- or metal-infused filaments and CF- or Kevlar-infused ABS as needing a hardened nozzle at 0.4 mm. Prusa lists its own ObXidian and nickel-plated hardened nozzles, and E3D's High Flow ObXidian and DiamondBack Nextruder nozzles. Prusa publishes a separate nozzle-change guide for the MK4 and MK3.9, so follow that one. Our replacement nozzle shortlist covers the options.

MMU3 notes

Prusa launched its Multi-Material Upgrade 3 alongside the MK4, and the launch post says it's "compatible with MK3S+ and MK4." Prusa's current MMU3 kit page is titled "for MK4S/MK3.9S," though its description calls the MMU3 "an add-on for the Original Prusa MK3.9/S and MK4/S." Check with Prusa which kit suits a plain MK4 before ordering. That page says the MMU3 "delivers the best performance, the same speed and the highest efficiency (lowest waste)" with "the standard nozzle in both MK4 and MK4S." The MK4 didn't ship with the MK4S's high-flow nozzle, so if you've kept the stock nozzle, there's nothing to swap for MMU printing.

Everyday PLA

PLA is the easiest material on an MK4, and none of the picks here needs an enclosure. Prusa's handbook says PLA "Prints best on a smooth (or satin) print sheet," so the stock sheet works.

Prusament PLA (Jet Black, 1 kg)

Prusament is Prusa's own filament brand, which makes it a straightforward choice on a Prusa printer. Prusa's material page lists a 210 ± 10 °C nozzle, a 40–60 °C bed, "Enclosure not required," and a temperature resistance of 55 °C. It lists low UV resistance and says it's "not ideal for outdoor use." Prusa lists "Low warping" among its pros and "Brittle" among its cons.

Prusa Research

Prusa Research Prusament PLA (Jet Black, 1.75 mm, 1 kg)

Best for

Precise everyday PLA prints, especially on Prusa printers with stock profiles.

Skip this if

The part needs heat, UV, or mechanical-stress resistance.

Specs, strengths, and limitations

Material

PLA

Diameter

1.75 mm

Net filament

1000 g (filament only, not packaged weight)

Format

plastic spool

Maker's nozzle range

200–220 °C

Strengths

• Manufacturer states diameter precision of ±0.02 mm and publishes measured data for every spool.
• Manufacturer states low warping, suitable for large prints.
• Manufacturer states guaranteed color consistency between batches.

Limitations

• Not suited to heat or outdoor use: Prusa lists 55 °C temperature resistance and low UV resistance.
• Prusa suggests PETG or PC Blend for mechanically stressed parts, and lists PLA as difficult to sand.

View on Amazon ↗ (opens Amazon in a new tab)Details checked 2026-10-06 against the manufacturer. Price and availability are on Amazon.

Skip it if the part will see heat, sun or repeated bending.

Polymaker PolyLite PLA (Black, 1 kg)

PolyLite PLA is a non-Prusament alternative that, like Prusament, needs no enclosure on the open MK4. Its TDS (V5.4) lists a 190–230 °C nozzle, a 25–60 °C bed, "Closure Chamber: No Needed," and a heat deflection temperature of 58 °C at 1.8 MPa. It ships on a cardboard spool.

Polymaker

Polymaker PolyLite PLA (Black, 1.75 mm, 1 kg)

Best for

Everyday PLA prints, prototypes, and display models where a documented, easy-printing PLA is wanted.

Skip this if

The part will sit in a hot car, near heat sources, or needs toughness beyond standard PLA.

Specs, strengths, and limitations

Material

PLA

Diameter

1.75 mm

Net filament

1000 g (filament only, not packaged weight)

Format

cardboard spool

Maker's nozzle range

190–230 °C

Strengths

• Manufacturer states PolyLite PLA is designed for reliability and ease of printing.
• Manufacturer TDS lists no enclosure needed and a wide 190–230 °C nozzle window.
• Manufacturer publishes a full TDS with mechanical, thermal, and drying data.

Limitations

• Not suited to parts exposed to heat: the TDS lists a heat deflection temperature of 58 °C (1.8 MPa).
• Cardboard spool: Polymaker says its spools have hardened edges that work in the AMS, but Bambu Lab's general AMS guidance recommends an adapter or ring for cardboard spools. Check your unit.

View on Amazon ↗ (opens Amazon in a new tab)Details checked 2026-10-06 against the manufacturer. Price and availability are on Amazon.

Skip it if the part will see heat, or you'd rather stay with Prusa's own filament.

Polymaker PolyLite PLA Pro (Black, 1 kg)

PolyLite PLA Pro is a PLA that Polymaker's TDS describes as "combining high toughness and high rigidity," for parts that need more toughness than standard PLA. Its TDS (V5.5) lists the same 190–230 °C nozzle range, a 30–60 °C bed, no closed chamber needed, and a heat deflection temperature of 58 °C at 1.8 MPa. So it still has PLA's heat limit.

Polymaker

Polymaker PolyLite PLA Pro (Black, 1.75 mm, 1 kg)

Best for

Functional PLA parts, props, and prototypes that need more drop resistance than standard PLA.

Skip this if

The part will see heat above about 55 °C (TDS HDT 58 °C at 1.8 MPa) or needs to flex.

Specs, strengths, and limitations

Material

PLA (PLA Pro (toughened PLA))

Diameter

1.75 mm

Net filament

1000 g (filament only, not packaged weight)

Format

cardboard spool

Maker's nozzle range

190–230 °C

Strengths

• Manufacturer states it combines high toughness and high rigidity with the ease of printing of regular PLA.
• TDS lists notched Charpy impact strength of 17.1 kJ/m² (X-Y).
• Manufacturer publishes a full TDS with mechanical, thermal, and drying data.

Limitations

• Not for heat: the TDS lists a heat deflection temperature of 58 °C (1.8 MPa), and Polymaker says it is not for projects needing high heat resistance or flexibility.
• Cardboard spool: Bambu Lab strongly advises a spool adapter or adapter ring for cardboard spools in the AMS.
• Polymaker now calls this the 'Old Formula' and sells a separate 'New Formula' Polymaker PLA Pro; check which version an Amazon listing ships.

View on Amazon ↗ (opens Amazon in a new tab)Details checked 2026-10-06 against the manufacturer. Price and availability are on Amazon.

Skip it if the part will sit somewhere warm or needs to flex.

PETG for functional parts

PETG suits brackets, clips and fixtures that need more heat resistance than PLA. Mind the stock sheet. Prusa's PETG guide says "Do not print on the smooth PEI sheet as the adhesion may be too strong!" and to apply glue stick if you use it anyway. The MK4 handbook gives the same advice: a textured or satin sheet needs no special preparation, but on smooth PEI you should apply "a thin layer of glue stick." Our PETG printing problems guide covers sticking, stringing and blobs. For the trade-offs between PLA and PETG, see our PLA vs PETG guide.

Prusament PETG (Jet Black, 1 kg)

Prusament PETG is Prusa's own PETG. Its TDS lists a 250 ± 10 °C nozzle and an 80 ± 10 °C heatbed, with satin, powder-coated or smooth PEI sheets, the last "with a glue stick." Prusa's material page says "Enclosure not required," gives a temperature resistance of 68 °C, and warns of "Strong adhesion to the bed - be careful when you're removing the print." It lists possible stringing as a con.

Prusa Research

Prusa Research Prusament PETG (Jet Black, 1.75 mm, 1 kg)

Best for

Functional parts, brackets, and larger prints that need more toughness than PLA.

Skip this if

The part needs heat resistance above about 68 °C (TDS HDT at 0.45 and 1.8 MPa), or you want a matte finish that hides layer lines.

Specs, strengths, and limitations

Material

PETG

Diameter

1.75 mm

Net filament

1000 g (filament only, not packaged weight)

Format

plastic spool

Maker's nozzle range

240–260 °C

Strengths

• Manufacturer states high strength and durability with low shrinking and warping.
• Manufacturer states diameter precision of ±0.02 mm and publishes measured data for every spool.
• Manufacturer states it is easier to sand than PLA.

Limitations

• Prusa lists possible stringing that may require occasional drying, and poor bridging.
• Strong bed adhesion: Prusa warns to take care removing prints, recommends textured, satin or PP sheets, and says to avoid smooth PEI (glue stick if used).
• Heat resistance tops out around 68 °C: the TDS gives HDT 68 °C at both 0.45 and 1.8 MPa.

View on Amazon ↗ (opens Amazon in a new tab)Details checked 2026-10-06 against the manufacturer. Price and availability are on Amazon.

Skip it if the part needs more heat resistance than PETG offers.

Polymaker PETG (Black, 1 kg)

Polymaker's current PETG is a high-flow formula. Its TDS (V3.0) lists a 240–260 °C nozzle, a 60–70 °C bed, speeds up to 300 mm/s and "Closure chamber: Not Needed." It recommends drying at 60 °C for 6 hours. It ships on a cardboard spool.

Polymaker

Polymaker PETG (Black, 1.75 mm, 1 kg (new formula))

Best for

Functional brackets and fixtures, indoors or in shade, that need more toughness than PLA.

Skip this if

You can't keep filament dry, or the part needs heat resistance well above 65 °C (TDS HDT at 1.8 MPa).

Specs, strengths, and limitations

Material

PETG (high-flow)

Diameter

1.75 mm

Net filament

1000 g (filament only, not packaged weight)

Format

cardboard spool

Maker's nozzle range

240–260 °C

Strengths

• Manufacturer states it is less brittle and more impact-resistant than PLA.
• Manufacturer states it prints without an enclosure and works with AMS and multi-material systems.
• Manufacturer states a high-flow formulation for speeds up to 300 mm/s with a 0.4 mm nozzle.

Limitations

• Moisture-sensitive: the TDS recommends drying at 60 °C for 6 h and printing from a dry box.
• Heat resistance is limited: the TDS lists HDT 65 °C at 1.8 MPa (69 °C at 0.45 MPa).
• Cardboard spool: Polymaker says its spools have hardened edges that work in the AMS, but Bambu Lab's general AMS guidance recommends an adapter or ring for cardboard spools. Check your unit.

View on Amazon ↗ (opens Amazon in a new tab)Details checked 2026-10-06 against the manufacturer. Price and availability are on Amazon.

Skip it if you can't keep filament dry.

TPU for flexible parts

Prusa's launch post says that on the MK4's Nextruder, "Filament is pushed into the nozzle by a large 35mm no-slip drive gear." Its handbook still says flexible materials "are not suitable for beginners" and require a lower print speed. Prusa's flexible materials guide says to loosen the idler, print slowly ("usually 20 mm/s," with a maximum "somewhere between 30 and 40 mm/s"), and keep the filament dry. It also says "If you print on a smooth or satin sheet, apply a separation layer on it," such as glue stick, while the textured sheet doesn't need one. Both spools below are 95A, the firmer end of common TPU. Our TPU compatibility guide explains hardness grades.

Polymaker PolyFlex TPU95 (Black, 0.75 kg)

PolyFlex TPU95's TDS (V5.4) lists Shore 95A, a 210–230 °C nozzle, a 25–60 °C bed, 30–50 mm/s printing, no closed chamber needed, and drying at 70 °C for 8 hours. The spool holds 0.75 kg on cardboard.

Polymaker

Polymaker PolyFlex TPU95 (Black, 1.75 mm, 0.75 kg)

Best for

Flexible covers, grips, bumpers, and seals on printers that handle 95A TPU.

Skip this if

You need a softer TPU than 95A, or fast print times, or your printer is set up as Bowden and you can't print very slowly (Polymaker highly recommends direct drive and says Bowden is possible only at very slow speeds).

Specs, strengths, and limitations

Material

TPU

Diameter

1.75 mm

Net filament

750 g (filament only, not packaged weight)

Hardness

95A

Format

cardboard spool

Maker's nozzle range

210–230 °C

Strengths

• Manufacturer states it is engineered to work on most desktop 3D printers without specialized hardware.
• Manufacturer states it can stretch over three times its original length.
• Manufacturer TDS lists shore hardness 95A and no enclosure needed.

Limitations

• Slow printing: the TDS recommends 30–50 mm/s.
• Spool holds 0.75 kg, not 1 kg.
• Cardboard spool: Polymaker says it redesigned its spool edges to spin well in the AMS, but its Flexible TPU FAQ says TPU is often too soft to feed through the AMS and suggests avoiding it. Bambu Lab also advises against TPU in the AMS and recommends an adapter or ring for cardboard spools.

View on Amazon ↗ (opens Amazon in a new tab)Details checked 2026-10-06 against the manufacturer. Price and availability are on Amazon.

Skip it if you want a 1 kg spool or a softer TPU.

Overture TPU 95A (Black, 1 kg)

Overture's product page lists 95A hardness, and its print-settings table gives a 210–240 °C nozzle and a 35–50 °C bed. The page's description says 210–230 °C, so its own figures differ slightly. It recommends drying at 70 °C for 7 hours, and warns that drying for too long can make the filament brittle.

Overture

Overture TPU 95A (Black, 1.75 mm, 1 kg)

Best for

General-purpose 95A flexible parts such as gaskets, seals, and protective cases.

Skip this if

You plan to feed it through a Bambu Lab AMS or AMS lite, or you want a TPU whose maker recommends it for Bowden printers.

Specs, strengths, and limitations

Material

TPU

Diameter

1.75 mm

Net filament

1000 g (filament only, not packaged weight)

Hardness

95A

Format

cardboard spool

Maker's nozzle range

210–240 °C

Strengths

• Manufacturer states its 95A Shore hardness balances softness and toughness for impact absorption and rebound.
• Manufacturer states it resists oil and recovers its shape after repeated stress.
• Manufacturer states unopened spools have a 1-year shelf life with proper storage.

Limitations

• The TPU printing tips on Overture's product page say 'Not compatible with AMS or other multi-material systems.'
• Overture marks it 'AMS & AMS lite NOT Compatible', and its FAQ says TPU is too soft for the AMS and can jam or extrude inconsistently.
• Overture's own documents disagree on bed temperature, drying time, and elongation (see notes).
• Manufacturer says to keep it dry before use.
• Overture's TPU wiki says to use a direct-drive system or an external extruder attachment, and its extruder wiki rates Bowden support for flexible filament as 'Limited'; the product page doesn't mention Bowden.

View on Amazon ↗ (opens Amazon in a new tab)Details checked 2026-10-06 against the manufacturer. Price and availability are on Amazon.

Skip it if you want one consistent set of maker settings.

Does the MK4 need an enclosure for ASA and ABS?

Prusa's ASA guide says "the bed should be heated to at least 100 °C, and the printer should be inside an enclosure to keep a higher ambient temperature." Its ABS guide says the same about the bed and says "the printer should be inside an enclosure." Both guides apply to the MK4 family. Prusa's MK4 handbook lists ASA's tendency to warp and says "printing in an enclosed box is recommended." Without an enclosure, Prusa suggests PrusaSlicer's draft shield as "one simple alternative," but that only keeps the model "slightly warmer."

Both guides warn that the material "releases fumes and substances that could pose a potential health risk," and say to print in a well-ventilated room without creating a draft around the print. The ABS guide also warns that "Printing inside an enclosure can lead to deformation of the fan shroud and other plastic parts," which "can affect the printer's functionality."

The sheet matters too. Prusa's handbook says ASA and ABS "work best with a satin print sheet," and that you need glue stick on a textured or smooth sheet. Our ABS vs ASA guide and enclosure planning guide cover the choice.

3D Sourcerer DELACK Enclosure Kit with LED Light

3D Sourcerer says the DELACK kit is "designed for the Bambu Lab A1 Mini, Prusa MK4, Prusa Mini, and Prusa MK3 series." The maker's description doesn't name the MK4S. The maker gives its size as 550 × 486 × 450 mm without saying which figure is width, depth or height. Prusa's handbook lists the MK4 at 460 mm wide, 420 mm deep with the bed centered and 385 mm tall without the spool. The bed moves front to back, so measure before you buy. It's a kit: the 3D-printed connector parts aren't included, and you print them from the maker's files. An LED light with a 5 V power brick is included. The maker doesn't list a fan or filter among the included parts. The back panel has a cutout for an optional 120 mm fan, and the maker offers printable mounts for a HEPA filter or a 4-inch exhaust duct. 3D Sourcerer publishes no heat limits for printer electronics inside the box. For other options, see the printer enclosures shortlist.

3D Sourcerer

3D Sourcerer DELACK 3D Printer Enclosure Kit with LED Light (DELACK_V1 kit, 550 x 486 x 450 mm, printed parts not included)

Best for

Prusa MINI and MK4 owners who want a compact clear box they can customize and print parts for.

Skip this if

You don't have a working printer to print the parts, or you want a ready-to-use enclosure.

Verified fit

Prusa Research MINI / MINI+ (MINI); Prusa Research MK4 (stock configuration, per the manufacturer)

Specs, strengths, and limitations

Maker notes

3D Sourcerer SKU DELACK_V1. The maker states the size as '550MM x 486MM x 450MM (21.7" x 19.1" x 17.7")', with a length matching an IKEA LACK table. It does not say which figure is width, depth, or height. The maker states it is 'designed for the Bambu Lab A1 Mini, Prusa MK4, Prusa Mini, and Prusa MK3 series'. The MK4 has a compatibility record. 'MK3 series' names a family, not an exact model, so no MK3S record is made; the MK4S is not named. KIT ONLY: 3D-printed parts are not included and must be printed from the maker's downloadable files. An LED light with a 5V power brick is included. The back panel has a cutout for an optional 120 mm fan. The maker offers printable mounts for a HEPA filter or a 4-inch exhaust duct, which are sold or printed separately. Bambu Lab's A1 mini FAQ says: 'We don't recommend enclosing the A1 mini.' We therefore do not list this kit for the A1 mini, even though 3D Sourcerer names it.

Strengths

• Manufacturer states it is designed for the Bambu Lab A1 Mini, Prusa MK4, Prusa Mini and Prusa MK3 series.
• Manufacturer states an LED light with a 5V power brick is included.
• Manufacturer provides printable mounts for a 120 mm fan, a HEPA filter, or a 4-inch exhaust duct.

Limitations

• Not for the Bambu Lab A1 mini: Bambu Lab says it doesn't recommend enclosing the A1 mini.
• Not a ventilation solution as shipped. No fan or filter is included; ventilation needs the optional fan plus a duct or filter you add. Plan ventilation separately.
• Follow your printer maker's guidance on enclosed operation and electronics heat. 3D Sourcerer publishes no heat limits for printer electronics inside.
• You must print the connector parts yourself, and the size suits small printers only.

View on Amazon ↗ (opens Amazon in a new tab)Details checked 2026-10-06 against the manufacturer. Price and availability are on Amazon.

Skip it if you want a ready-to-use enclosure, or you'd rather buy Prusa's own MK4/S Enclosure.

Prusament ASA (Natural, 800 g)

Prusa's material page lists a 260 ± 5 °C nozzle, a 110 ± 5 °C bed and "Skirt or Enclosure Recommended." Its data sheet (v1.1) gives the nozzle as 260 ± 10 °C. The material page calls ASA "UV stable" and gives a high-temperature resistance of up to 93 °C. It recommends the satin sheet, and says that on the powder-coated or smooth sheet "the adhesion of the material can be too strong," so use glue on those. The spool holds 800 g, and it's sold in Natural rather than black.

Prusament

Prusament ASA (Natural, 1.75 mm, 800 g)

Best for

Prusa owners and anyone who wants a thoroughly documented, UV-stable ASA for outdoor parts.

Skip this if

Your bed can't reach 110 °C or you print in an unventilated room.

Specs, strengths, and limitations

Material

ASA

Diameter

1.75 mm

Net filament

800 g (filament only, not packaged weight)

Format

other

Maker's nozzle range

250–270 °C

Strengths

• Manufacturer states ASA is UV stable and shows no deformation up to about 93 °C.
• Prusa publishes a full TDS and measures diameter along every spool.
• Manufacturer states it can be smoothed with acetone vapor and sanded wet or dry.

Limitations

• Spool holds 800 g, less than the 1 kg spools here.
• Needs a 110 °C bed, and Prusa recommends an enclosure or tall skirt to control warping.
• Prusa warns of styrene fumes and recommends ventilation or an enclosure with active filtration.

View on Amazon ↗ (opens Amazon in a new tab)Details checked 2026-10-07 against the manufacturer. Price and availability are on Amazon.

Skip it if your MK4 isn't enclosed, or you want a 1 kg spool.

Polymaker ASA (Black, 1 kg)

Polymaker's ASA TDS (V6.0) lists a 230–260 °C nozzle, a 75–95 °C bed, the cooling fan off, "Closure chamber: Needed," and a heat deflection temperature of 100 °C at 1.8 MPa. It recommends drying at 70 °C for 7 hours. Its bed range is below the 100 °C or more that Prusa's ASA guide recommends, so you have two sets of advice to choose from. It ships on a cardboard spool.

Polymaker

Polymaker ASA (Black, 1.75 mm, 1 kg)

Best for

Outdoor and sun-exposed functional parts printed on an enclosed machine.

Skip this if

Your printer is open-frame or can't reach a 95 °C bed and 260 °C nozzle.

Specs, strengths, and limitations

Material

ASA

Diameter

1.75 mm

Net filament

1000 g (filament only, not packaged weight)

Format

cardboard spool

Maker's nozzle range

230–260 °C

Strengths

• Manufacturer states it is an alternative to ABS with improved weather and UV resistance.
• Manufacturer TDS lists a heat deflection temperature of 100 °C (1.8 MPa).
• Manufacturer states it prints with settings very similar to ABS.

Limitations

• Needs an enclosed printer per the TDS.
• Requires higher nozzle and bed temperatures (230–260 °C, 75–95 °C) than PLA or PETG.
• Cardboard spool: Bambu Lab strongly advises a spool adapter or adapter ring for cardboard spools in the AMS.

View on Amazon ↗ (opens Amazon in a new tab)Details checked 2026-10-06 against the manufacturer. Price and availability are on Amazon.

Skip it if your MK4 isn't enclosed.

Polymaker PolyLite ABS (Black, 1 kg)

PolyLite ABS's TDS (V5.5) lists a 245–265 °C nozzle, a 90–100 °C bed, the cooling fan off and a closed chamber as "Needed (ambient temperature)." It lists a heat deflection temperature of 98 °C at 1.8 MPa and drying at 70 °C for 6 hours. It ships on a cardboard spool. If you're choosing between them, Prusa's handbook says ASA "is UV-stable compared to ABS and shrinks slightly less during printing."

Polymaker

Polymaker PolyLite ABS (Black, 1.75 mm, 1 kg)

Best for

Heat-resistant functional parts, enclosures, and prototypes printed on an enclosed printer.

Skip this if

Your printer is open-frame or its bed can't reach 90 °C.

Specs, strengths, and limitations

Material

ABS

Diameter

1.75 mm

Net filament

1000 g (filament only, not packaged weight)

Format

cardboard spool

Maker's nozzle range

245–265 °C

Strengths

• Manufacturer states PolyLite ABS uses a bulk-polymerized ABS resin with significantly lower volatile content than traditional ABS, for minimal odor.
• TDS lists a heat deflection temperature of 98 °C at 1.8 MPa.
• Manufacturer publishes a full TDS with mechanical, thermal, and drying data.

Limitations

• TDS lists a closed chamber as 'Needed'. Polymaker's product page says a non-enclosed printer with a 90 °C bed and 260 °C nozzle can handle models smaller than fist size, larger prints need an enclosed printer (about 40–50 °C), and models over about 15–20 cm need a heated chamber (about 70 °C or more).
• Needs a 90–100 °C bed (TDS), so printers with low-temperature beds aren't suitable.
• Cardboard spool: Bambu Lab strongly advises a spool adapter or adapter ring for cardboard spools in the AMS.

View on Amazon ↗ (opens Amazon in a new tab)Details checked 2026-10-06 against the manufacturer. Price and availability are on Amazon.

Skip it if your MK4 isn't enclosed, or the part will live outdoors.

Carbon fiber: fit a wear-resistant nozzle first

E3D ObXidian Prusa Nextruder Nozzle (0.4 mm)

E3D's product page says the nozzle is "Compatible with Prusa's MK3.9, MK3.9S, MK4, MK4S, XL, CORE One & CORE One L 3D printers." E3D lists a 300 °C maximum. E3D says the coating gives "orders-of-magnitude higher durability for abrasive filaments like carbon fiber, glass fiber filled materials." It also warns that aggressive fillers, such as Polymaker's Fiberon PA612-CF, PA6-CF, PA6-GF and PA12-CF, can still cause significant wear, and that glow-in-the-dark filaments contain a very hard additive. Some filled materials can jam nozzles of 0.4 mm and smaller, so check the filament maker's minimum nozzle size. E3D also sells a 0.6 mm size.

E3D

E3D ObXidian Prusa Nextruder Nozzle (0.4 mm, single nozzle (PRUSA-MK4-NOZZLE-OBX-AS-0400))

Best for

Nextruder owners (MK4, MK4S, XL, CORE One, CORE One L) who print carbon-fiber, glass-fiber or glow filaments regularly.

Skip this if

You print only plain PLA and PETG, where a brass Nextruder nozzle does the job.

Verified fit

Prusa Research MK4S; Prusa Research CORE One; Prusa Research CORE One L; Prusa Research XL; Prusa Research MK4 (stock configuration, per the manufacturer)

Specs, strengths, and limitations

Interface

Prusa Nextruder nozzle with all-metal filament guide

Hotend design

Tool steel insert with E3DLC coating

Part rated to

300 °C (your printer's own hotend limit may be lower)

Wear-resistant

Yes, per the manufacturer

Maker notes

E3D product page: compatible with Prusa MK3.9, MK3.9S, MK4, MK4S, XL, CORE One & CORE One L. MK3.9/MK3.9S are not in printers.json. Amazon listing says MK4 and XL only; E3D's current page (manufacturer) also names MK4S, CORE One and CORE One L. Prusa Knowledge Base: every MK4S, MK3.9S, MK4, MK3.9, XL, CORE One/+, CORE One L/+ and Signature Oak printer has a Nextruder hotend. Each nozzle has its size engraved (E3D).

Strengths

• Manufacturer states wear resistance orders of magnitude higher than any other E3D nozzle, for abrasive/filled polymers.
• Manufacturer states the E3DLC coating adds non-stick properties for less plastic build-up.
• Manufacturer names the MK4, MK4S, XL, CORE One and CORE One L as compatible.

Limitations

• E3D lists a 300 °C maximum recommended printing temperature.
• E3D warns aggressive fillers (e.g. Polymaker Fiberon PA612-CF, PA6-CF, PA6-GF, PA12-CF) can still cause significant wear, and some filled materials can jam nozzles of 0.4 mm and smaller.

View on Amazon ↗ (opens Amazon in a new tab)Details checked 2026-10-06 against the manufacturer. Price and availability are on Amazon.

Skip it if you print only plain PLA, PETG, TPU, ASA and ABS, where the stock brass nozzle does the job.

Polymaker PolyLite PLA-CF (Black, 1 kg)

PolyLite PLA-CF is PLA with 8% chopped carbon fiber, for stiff, matte parts. Polymaker's product page says a hardened nozzle is strongly recommended and lists "0.4mm+ hardened nozzle required." The TDS (V5.4) lists a 190–230 °C nozzle, a 25–60 °C bed and no closed chamber needed. The TDS lists a heat deflection temperature of 50 °C at 1.8 MPa, lower than plain PolyLite PLA.

Polymaker

Polymaker PolyLite PLA-CF (Black, 1.75 mm, 1 kg)

Best for

Stiff, matte-finish PLA parts and prototypes on a printer fitted with a hardened nozzle.

Skip this if

Your printer only has a brass nozzle, or the part will see heat.

Specs, strengths, and limitations

Material

PLA (carbon-fiber filled (8 wt% chopped carbon fiber))

Diameter

1.75 mm

Net filament

1000 g (filament only, not packaged weight)

Format

cardboard spool

Maker's nozzle range

190–230 °C

Nozzle

Abrasive: the maker recommends a wear-resistant nozzle

Strengths

• Manufacturer states 8% chopped carbon fiber gives exceptional rigidity and strength.
• Manufacturer states a matte black finish with virtually invisible layer lines and low shrinkage.
• Manufacturer states it prints with standard PLA settings; the TDS lists no enclosure needed.

Limitations

• Abrasive: Polymaker strongly recommends a hardened nozzle.
• Not suited to heat: the TDS lists a heat deflection temperature of 50 °C (1.8 MPa).
• Cardboard spool: Bambu Lab strongly advises a spool adapter or adapter ring for cardboard spools in the AMS.
• The Amazon listing's bullet points describe plain PolyLite PLA, though its title and model number (PA10001) are the carbon-fiber version. Check that the title says Carbon Fiber PLA before you buy.

View on Amazon ↗ (opens Amazon in a new tab)Details checked 2026-10-06 against the manufacturer. Price and availability are on Amazon.

Skip it if you still have the brass nozzle fitted, or the part will see heat.

Polymaker Fiberon PETG-rCF08 (Black, 0.5 kg)

Fiberon PETG-rCF08 is PETG with 8% recycled carbon fiber, per Polymaker's product page. Its TDS (V1.0) lists a 240–270 °C nozzle, a 60–70 °C build plate and a room-temperature chamber. It says brass nozzle wear "happens frequently," with a brass nozzle lasting "approximately 9h," and highly recommends a wear-resistant nozzle such as hardened steel or ruby. The product page's spec block says "Enclosure Not needed," but its printing tips say "An enclosed printer is recommended," and that "If an open-frame printer needs to be used," Polymaker's preset files are recommended. The MK4 is an open-frame printer. It recommends drying at 65 °C for 3 hours. The spool holds 0.5 kg. For more filled options, see the carbon fiber filament shortlist.

Polymaker

Polymaker Fiberon PETG-rCF08 (Black, 1.75 mm, 0.5 kg)

Best for

An easy first carbon-fiber PETG for matte functional parts and fixtures on a printer with a hardened nozzle.

Skip this if

You need parts that hold up above about 65 °C, or you want a 1 kg spool.

Specs, strengths, and limitations

Material

PETG (8% recycled carbon-fiber filled)

Diameter

1.75 mm

Net filament

500 g (filament only, not packaged weight)

Format

other

Maker's nozzle range

240–270 °C

Nozzle

Abrasive: the maker recommends a wear-resistant nozzle

Strengths

• Manufacturer states 8% recycled carbon fiber for added stiffness over standard PETG.
• Manufacturer states a matte finish that hides layer lines and PETG-level low warping.
• Prints at ordinary PETG temperatures (240–270 °C nozzle, 60–70 °C bed) per the TDS, with only a short 65 °C / 3 h dry.

Limitations

• Abrasive: Polymaker requires a hardened (or ruby) nozzle of 0.4 mm or larger; brass lasts about 9 h.
• Modest heat resistance: TDS heat deflection temperature is 65.7 °C at 1.8 MPa.
• Only sold in 0.5 kg and 3 kg spools, and Polymaker's enclosure guidance is inconsistent between page sections.

View on Amazon ↗ (opens Amazon in a new tab)Details checked 2026-10-07 against the manufacturer. Price and availability are on Amazon.

Skip it if you still have the brass nozzle fitted, or want a 1 kg spool.

What we left out

• PC. Prusa's launch post says the MK4 can print polycarbonate, but the only plain PC spool in our catalog, Polymaker PolyLite PC, lists "Closure Chamber: Needed (70-100˚C)" in its TDS. Prusa describes its MK4/S Enclosure as passive, heated only by the bed, and lists a 45 °C maximum chamber temperature in it, so we haven't included it.
• Prusament PC Blend Carbon Fiber. Prusa's material page gives a nozzle temperature of 285 ± 10 °C, a range that goes beyond the 290 °C figure we use.
• Nylon carbon-fiber grades. Polymaker's Fiberon PA6-CF20, PA12-CF10 and PA612-CF15 data sheets list nozzle ranges up to 300 °C, above the 290 °C figure we use, and E3D names those Fiberon nylons among the fillers that can still wear ObXidian. ELEGOO says its PAHT-CF needs an enclosed printer, and SUNLU's enclosure guide strongly recommends an enclosure for nylon, which an open MK4 doesn't have.

Checklist before you buy for an MK4

• Which printer you have. If you've fitted the MK4S upgrade kit, use our CORE One and MK4S page.
• Material vs. enclosure. PLA, PETG and TPU work in the open. ASA and ABS need an enclosure, per Prusa's guides.
• Temperatures. Keep to 290 °C on the nozzle and 120 °C on the bed. Check the spool's published range.
• Stock smooth PEI sheet. Use glue stick on it for PETG, TPU, ASA and ABS. Prusa's handbook says a textured sheet needs no separation layer for PETG or TPU, and a satin sheet needs no preparation for PETG, ASA or ABS.
• Abrasive fills. Carbon fiber, Kevlar, glass, wood and metal fills need a wear-resistant Nextruder nozzle, not the stock brass.
• Spool weight. Prusament ASA is 800 g, PolyFlex TPU95 is 0.75 kg and Fiberon PETG-rCF08 is 0.5 kg. Everything else here is 1 kg.

Drying, storage and safety

Several spools here need dry storage. Prusa says flexible filaments "tend to absorb moisture and can be hard to print when wet," and its ASA guide lists ASA as "Partially hygroscopic." Polymaker "highly" recommends a PolyBox or PolyDryer box for its PETG, and says Fiberon PETG-rCF08 "is sensitive to moisture." Each maker's drying setting is on its product card above. Use the setting for your exact spool, and check the spool's own temperature rating before drying it on the spool. Our filament dryer vs dry box guide covers the options.

How this page was checked

This is a research-based page. We have not printed these spools on an MK4 for it, so it contains no test results or scores. The printer facts come from Prusa's MK4 and MK3.9 handbook (v1.03), the MK4 and MK4S launch posts, the MK4-to-MK4S upgrade kit page, the MK4S product page, the Original Prusa MK4/S Enclosure page, the MMU3 product page, the Nextruder nozzle guide and the Prusa Knowledge Base material guides. Prusa's MK4 product page now redirects to the MK4S, so we couldn't use it. The spool, nozzle and enclosure statements come from each maker's own pages and data sheets, listed in the sources section. All were retrieved on 2026-10-14. Makers update their pages, so check the current version before relying on a number. Read more in our editorial standards and affiliate disclosure.

PLA: what to check before you buy a spool ↗