At a glance, the Original Prusa MK4 ($1,099 as tested, pre-assembled; $799 in kit form) appears much the same as the Editors' Choice-award-winning Original Prusa i3 MK3S+. But don't just pass it over, since the MK4 provides some important modifications over that previous-generation model: a thicker frame, a redesigned extruder, a touch screen, and an improved bed-leveling system. In our testing, the new model consistently produced high-quality prints, and it presented no operational problems during our time with it. With the MK4, Prusa Research has maintained its excellence in developing open-frame 3D printers, and the MK4 takes the baton as our latest Editors' Choice honoree among reasonably priced filament-based printers for hobbyists and makers.

Design: A Classic Open-Frame Printer

Orange isn't the new black with the MK4; it simply is orange and black. Clad in Prusa's signature colors, the MK4 is Prusa Research's flagship 3D printer, directly descended from the Prusa I2 which the Czech company sold at its 2012 inception. The open-frame MK4, a single-extruder model, measures 15 by 19.7 by 22 inches (HWD), excluding the spool and spool holder, which sit atop the print bed. (The device comes with two spool-holder rods, so you can feed filament to the extruder with one spool and have an auxiliary spool at the ready.)

(Credit: Joseph Maldonado)

The frame consists of a base that supports a square arch to which the vertical and horizontal carriages are attached. Along these carriages the redesigned "Nextruder" moves.

(Credit: Joseph Maldonado)

The base also supports the build plate, which can move in and out (toward or away from the front of the printer). In front of the build plate is a black panel housing an LCD, with a control knob and a port for a USB thumb drive on the right side.

(Credit: Joseph Maldonado)

The print area for the MK4, at 9.8 by 8.3 by 8.6 inches (HWD), is a smidge larger than its predecessor's 9.8 by 8.3 by 8.3 inches. It's also slightly larger than that of the Anycubic i3 Mega S (8.1 by 8.3 by 8.3 inches) and considerably bigger than the 7-inch-cubed print volume of the Original Prusa Mini.

(Credit: Joseph Maldonado)

You can save more than $300 by assembling your Original Prusa MK4 from a kit or order it ready to go out of the box for $1,099, as our test unit is. (Note that on purchases of $800 or more, US customers may have to pay an import duty upon receiving the shipment from the Czech Republic.) As the MK4 is open-source, part of the venerable RepRap tradition—Prusa Research 3D-prints the plastic parts used in its construction—several companies have created Prusa clones that they market for a lower price. However, their build quality is indeterminate, and we suggest that you stick with the real deal: an Original Prusa printer.

Documentation, Accessories, and Software

The MK4 includes a superb physical user manual, the 3D Printing Handbook. Unlike most 3D printer manuals, which tend to be spartan, confusing, and often incomplete (and frequently online-only), the Handbook is a beautiful, professionally printed guide that covers both the pre-assembled version and the kit.

Our printer also comes with another signature Prusa accessory: a package of Haribo Goldbären, a.k.a. Gummi Bears. With Prusa's kits, you are supposed to eat the bears as a reward for completing certain steps specified in the assembly guide, but no such restrictions apply to the pre-assembled version—at least I assume that was the philosophy espoused by whoever took and presumably devoured our stash of bears that was hanging around PC Labs. [Editors' Note: As it turns out, PCMag's lab director actually stashed them in a cabinet for safe eating...er, keeping, alongside the spare filament.]

The MK4 includes a toolset: several wrenches, including Allen and Torx keys; a Philips screwdriver; and needle-nose pliers.

(Credit: Prusa Research)

For software, the MK4 relies on the company's PrusaSlicer, which we have seen in the previous Prusa 3D printers we reviewed. The software, which resembles the popular Ultimaker Cura program, is easy to master, leading you through loading a 3D file, modifying it, "slicing" it to printable form, and saving it. PrusaSlicer has three interfaces or user levels. Simple offers a basic range of settings and is designed to get you up and printing quickly, while the Advanced and Expert modes provide a more comprehensive range of tweaks.

(Credit: Joseph Maldonado)

An Abundance of Supported Filament Types

As a filament-based (FFF, for fused filament fabrication) 3D printer, the Original Prusa MK4 supports an extensive variety of filament types, including but not limited to PLA (polylactic acid), PETG (polyethylene terephthalate enhanced with glycol), ABS (acrylonitrile butadiene styrene), ASA (acrylonitrile-styrene-acrylate, an alternative to ABS), Flex, nylon, carbon-filled, and Woodfill. The MK4 comes with a 1-kilogram spool of PLA filament, which is what I used for most of our testing.

(Credit: Joseph Maldonado)

The pre-assembled MK4 required very little work to get up and running. It arrives with a test print already printed out and adhered to the build plate. You gently pry it off, assemble the spool holder—which snaps into place on the metal bar atop the printer—and then turn the printer on.

(Credit: Joseph Maldonado)

It first runs through a self-test and calibration routine. You then use the LCD's control knob to extract the remaining filament from the extruder, twist the knob to the Filament In setting, put a spool of filament on the holder, and feed it into the extruder. (A recent firmware update has endowed the LCD with touch-screen functionality, so you can ignore the knob and stick to taps and swipes if you prefer.) Filament should soon start extruding from the nozzle; pressing Yes when prompted will stop the flow. You remove the filament strand hanging from the nozzle, plug in the supplied USB thumb drive, select a sample file, and press Print.

Testing the Original Prusa MK4: The Usual Superior Prusa Quality

I printed 10 objects on the MK4 at the default "Quality" resolution setting. While several prints were from test files included on the USB thumb drive that came with the MK4, most were selections from our usual suite of test items.

Print quality was very similar to the i3 MK3S+: generally above average, with only minor blemishes, most commonly an occasional and easily removed tail of loose filament. I experienced one misprint: an Apollo Lunar Lander and Command and Service Module combo. In fairness to the MK4, the PrusaSlicer software had identified aspects of the file as potentially problematic, but I went and printed it anyway. (Previous versions of PrusaSlicer wouldn't even let the object load.)

(Credit: Joseph Maldonado)

The MK4 did a magnificent job printing the shapes and text on the highly inclined geometric test object. The shapes were all well-formed, and the text readable to the smallest size. It printed the object's frame with only the slightest hint of warping, which is better than most filament-based printers we have reviewed.

(Credit: Joseph Maldonado)

While, as a rule, we do not formally drag-race 3D-printing speed between different 3D printers (there being too many variables in resolution and other factors), the MK4 was quicker in printing some of our familiar test objects than is the norm.

Verdict: Prusa Takes 3D Printing to the Power of Four

With the Original Prusa MK4, Prusa has kicked off the fourth generation of the company's flagship open-frame 3D printer with several minor and several significant enhancements to its time-honored design, including a thicker aluminum frame, a redesigned extruder, a touch screen, and an improved bed-leveling system. It retains its superior print quality and ease of use while adding a speed boost.

(Credit: Joseph Maldonado)

The MK4 is the culmination of nearly a decade of refinements to the company's leading 3D printer. It supports printing with a wide variety of filaments, includes the simple-yet-powerful PrusaSlicer software, and comes with a handsome and helpful user manual as well as access to Prusa's extensive help resources and user forums.

The MK4 is priced at the high end of open-frame printers with similar build volumes; you can find good budget 3D printers such as the Creality Ender-3 S1 Pro, the AnkerMake M5C 3D Printer, and the Editors' Choice-winning Anycubic Kobra 2 for less than half its price. But if you don't mind paying for proven excellence, the Original Prusa MK4 easily earns our Editors' Choice honors as a mid-priced consumer-grade 3D printer.