What is the cheapest possible, real 3D printer you can buy without making one compromise after the other? That’s the question we’re asking by building a Prusa i3 MK2-style 3D printer that comes with most of the important features of the original one from Josef Prusa and requires a bit more work for sourcing and building the machine, but most importantly, we’re going to build it only with the most affordable set of parts.
This page will serve as a hub for part lists and build guides as the project moves along! All build videos and the accompanying project videos have been organized into a neat playlist!
Electronics and extruder
Each of these parts were picked for a reason – be it because they are better than the alternatives, or, as expected, simply cost less than anything else. You can find the full explanation and the accompanying video on its own page, but here are the lists of parts we’ve covered so far!
Electronics
Part | Function | Qty needed | Cheapest offer | Seen at |
---|---|---|---|---|
Mechanical endstop boards | Endstops | 2 | $0.34 | Aliexpress |
Reprap heated bed aluminum | Heated bed | 1 | $6.42 | Aliexpress |
100K BTC with cable | Heated bed temperature sensor | 1 | $0.52 | Aliexpress |
RAMPS 1.4 | Mainboard | 1 | $3.69 | Aliexpress |
Arduino Mega 2560 clone | Mainboard | 1 | $7.13 | Aliexpress |
12V 20A power supply | Power supply | 1 | $14.79 | Aliexpress |
A4988 driver | Stepper motor drivers | 4 | $0,73 | Aliexpress |
Reprap 14pcs wire set | Wiring | 1 | $3.05 | Aliexpress |
Optional parts
Part | Function | Qty needed | Cheapest offer | Seen at |
---|---|---|---|---|
LCD Controller, character-based version | LCD and SD card reader | 1 | $7,49 | Aliexpress |
LCD Controller, graphical version | LCD and SD card reader | 1 | $9.49 | Aliexpress |
IEC socket | Power input | 1 | $1.17 | Aliexpress |
Rocker switch | Power switch | 1 | $0.99 | Aliexpress |
Extruder Assembly
Part | Function | Qty needed | Cheapest offer | Seen at |
---|---|---|---|---|
5V M8 inductive sensor | Z probe | 1 | $5.09 | Aliexpress |
1.2mm Extruder springs (pack of 10) | Extruder springs | 1 | $0.96 | Aliexpress |
Hobbed gear | Filament drive gear | 1 | $0.80 | Aliexpress |
E3D v6 Jhead with fan and thermistor | Hotend | 1 | $5.00 | Aliexpress |
2x4mm bowden tube | Hotend-extruder liner | 1 | $0.80 | Aliexpress |
50mm radial fan | Part cooling fan | 1 | $1.16 | Aliexpress |
625 bearing | Extruder idler bearing | 1 | $1.50 (10-pack) |
Update: Thx to the hint from FB User David Kiddell we now know about this better Mk2 Extruder Design from Geoff Sim on Thingiverse.
Frame and motion
The frame is a fairly standard i3 type – you could go with a kit or make it yourself. The cutting template can be downloaded here, a .dxf file for CNC routing or lasercutting can be found on Prusa’s github!
Frame and fasteners
The fasteners have been adapted to work with a thicker frame and to make use of the alternative components used in this build. If you don’t want to cut the frame yourself , you can also buy one!
Part | Function / note | Qty needed | Cheapest offer | Seen at |
---|---|---|---|---|
18mm or 3/4" plywood/OSB/... | Frame material | 370x370mm | ~$1.00 | |
Optional: Thinner material (10mm or 3/8") for bed carriage | Bed frame material | 225x225mm | ~$1.00 | |
M3x10 cap-head screw (DIN912) | 16 | |||
M3x18 cap-head screw (DIN912) | 18 | |||
M3x20 cap-head screw (DIN912) | 7 | |||
M3x30 cap-head screw (DIN912) | 21 | |||
M3x40 cap-head screw (DIN912) | 3 | |||
M3 nut (DIN934) | 42 | |||
M3 nyloc nut (DIN985) | Locknut, alternatively jam two regular nuts or use threadlock | 4 | ||
M3 square nut slim (DIN562) | 6 | |||
M3 washer (DIN125) | 22 | |||
M3 fender washer (DIN9021) | 30 | |||
M5 nut (DIN934) | 2 | |||
M5 threaded rod (DIN976) | cut to 2pcs of 350mm | 1m | ||
M8 nut (DIN934) | alternatively slim nuts for aesthetics | 22 | ||
M8 washer (DIN125) | 22 | |||
M8 threaded rod (DIN976) | cut to 4pcs of 205mm | 1m | ||
M10 nut (DIN934) | alternatively slim nuts for aesthetics | 14 | ||
M10 fender washer (DIN9021) | 4 | |||
M10 washer (DIN125) | Can be replaced by fender washers with new printed part | 8 | ||
3D printed parts | Substitute the parts linked below for compatibility with the components listed here | 1 set | Github | |
M10 threaded rod (DIN976) | cut to 2pcs of 360mm | 1m | ||
2.5x100mm zip ties | like, 100 | Amazon |
Linear motion
What’s listed here is the way I’m building this printer, an even cheaper option would be to go with IGUS bushings and generic 8mm smooth rods!
Part | Function | Qty needed | Cheapest offer | Seen at |
---|---|---|---|---|
8mm smooth rods, 320m, 330 or 350mm, 370mm | X, Y Z linear guide | 2 each size | $26.98 | Aliexpress |
LM8UU bearings | X, Y, Z linear bearings | 10 | $5,70 | Aliexpress |
GT2-2M 6mm belt (often just called "GT2") (set with pulleys) | X, Y belt | 2m | $0.52 | Aliexpress |
GT2-2M 16T pulleys, 5mm bore (set with belt) | X, Y belt pulleys | 2 | - | |
GT2-2M 16T idler pulley, 3mm bore | X, Y belt idlers | 2 | $2.48 | Aliexpress |
NEMA17 stepper motor | X, Y, Z (x2), E stepper motors | 5 | $41.00 | Aliexpress |
5x5mm flexible coupler | Z-axis coupler | 2 | $1.60 | Aliexpress |
Printed parts
Most of the printed parts are the exact ones from the MK2, however you don’t need all of them and a few have been modified to make them work with the cheaper components. Where possible, they should still be compatible with the original parts.
To get them printed, you might get lucky on eBay or print them yourself at a local FabLab or Makerspace.
Standard parts
These are from PrusaResearch’s Github page
Part | Qty needed |
---|---|
extruder-body.stl | 1 |
extruder-cover.stl | 1 |
extruder-idler.stl | print modified design |
fan-nozzle.stl | 1 |
x-carriage.stl | 1 |
x-end-idler.stl | 1 |
x-end-motor.stl | print modified design |
y-belt-holder.stl | 1 |
y-corners.stl | 2 for 350mm Y smooth rods, 4 for 330mm Y smooth rods |
Y-distance.stl | 1 |
y-idler.stl | 1 |
y-motor.stl | print modified design |
z-axis-bottom.stl | 1 |
z-axis-top.stl | 1 |
Modified parts
Also based on the original MK2 files, but modified for the parts suggested for this build. These parts are attached at the bottom of this page!
Part | Qty needed |
---|---|
Z-nut holdah x4.stl | 4 |
extruder-idler (simplified) x1.STL | 1 |
x-end-motor (new endstops) x1.stl | 1 |
y-corners (open) x2.STL | 2, for 350mm smooth rods 0, for 330mm smooth rods |
y-motor (new endstops) x1.STL | 1 |
Optional parts
With the standard and modified parts, you should be able to build a 3D printer capable of printing its own upgrades. The following parts are non-essential addons, like an LCD mount or bed probe protector. While these can be a starting point, there are plenty of alternative parts and upgrades available on Thingiverse and Youmagine!
Part | Qty needed |
---|---|
LCD-cable-clip.stl | A few |
LCD-knob.stl | 1 |
LCD_SupportA.stl | 1 |
LCD_SupportB.stl | 1 |
LCD_cover.stl | 1 |
PINDA_protector.stl | 1 |
Stay tuned as we move on with the build of the super-cheap Prusa i3 MK2. This page will get updated as progress is made!