Tag Archives: K’NEX 3D Printer

Building a $60 SLA 3D printer with LEGO and K’NEX

Don’t want to spend big bucks on an SLA printer but tired of FDM? Make your own with LEGO, K’NEX and Arduino.

While the market for 3D printers has surely grown throughout the years, up until now a majority of Makers have turned to Fused Deposition Modelling (FDM) machines. These work by heating a material, extruding it out of a moving nozzle and giving it time to cool. On the contrary, Stereolithography revolves around UV lighting to harden the liquid resin, which enables Makers to create projects in one piece and with smoother surfaces. However, this convenience comes at a cost. Those seeking a higher resolution print have no choice to dig deep into their wallets for an SLA device. Unless, you are Instructables users “mastsermind,” who has created one for less than $60 using some LEGO bricks, K’NEX pieces and a few other electronic components.


Inspired by the mythological creature comprised of three different animals, the Chimera 3D printer is made up of recycled parts from three different categories: projectors, toys and old computers. What’s impressive is that the unit doesn’t entail a whole lot of parts: just a projector, a computer disc drive laser deck with stepper motor, any ATmega328 based Arduino, an EasyDriver v.4.4, some tools and wires, along with the option to etch a circuit board and construct a wooden frame. That’s it.

“Top down DLP printers in their simplest form have only one axis of motion, a video projector, and minimal electronics. They do not require a heated or perfectly level bed, there is never a clogged or wrong temperature in the extruder as it does not use an extruder. And the resin used has a comparable price to FDM printers,” the Maker explains.


The Chimera was built around two frames, one of LEGO to hold the Z axis, platform and resin tank, the other of K’NEX to hold and move the projector. Beyond that, the resin tank can basically be any container that’s waterproof and strong enough to hold the solvent.

Obviously, the most important component of the system is the projector, which matsermind employed an inexpensive Mitsubishi XD221u. He does recommend staying above a 1024 x 768 resolution for optimal results. In order to make this suitable for printing, a few modifications are required such as getting the focus distances closer and removing the UV filter to allow for more light through.

“Making it cure the resin faster is easy, just remove the filter (glass square) on the front of the bulb.  Making the projector focus at ≈7 inches was a bit more difficult. The service manual has been attached for assistance in disassembly if you are using an XD221u projector, but the modification should be similar for most projectors,” the Maker reveals.


Meanwhile, the Z axis consists of a laser deck assembly from an old computer disc drive. An Arduino is tasked with driving the stepper motor salvaged from the drive and ensuring it moves at the right rate.

“The one I used is one that I have had around for a while, waiting for a good use for it. I do not know what model drive it came out of, but any assembly will work as long as it uses a stepper motor with four wires and not a DC motor with two wires,” he adds.

What’s nice about a top down system is the simplicity of its electronics. Whereas a vast majority of complex printers today are embedded with the combination of an Arduino Mega (ATmega2560) and a RAMPS 1.4 shield, this machine only requires an inexpensive Arduino Uno seeing as though there is only one axis to control.


“If you want to put a little more work into it, you can program an ATmega328 chip with the firmware and etch an all-in-one board whose design is included in the files attached,” matstermind notes.

In terms of firmware, the Maker selected GRBL 0.9i and runs the open source Creation Workshop software on it. While as fully-functional as it may be, mastermind has a few more plans for Chimera in the weeks to come. These include increasing the size of the resin tan, designing a wooden frame out of MDF or particle-board shelving, enhancing its stability, as well as adding a shutter attachment to prevent the resin from being exposed to accidental light.

Intrigued? Head over to the project’s elaborate Instructables page here.