Unfortunately building a controller is outside the scope of this Instructable. However the stepper motors used by this machine are very low current, and are unipolar, meaning that there are a wide range of DIY and commercial controllers available.
Other projects which could control this machine include:
- Makerbot Electronics http://store.makerbot.com/electronics/assembled-electronics.html
You would need the motherboard and three driver boards, which totals about $205
- GRBL http://www.contraptor.org/grbl-gcode-interpreter
This is an open-source gcode interpreter.
- MakeYourBot Controller based on EMC2 http://makeyourbot.org/electronics-and-software
- Anything based on the ULN2003. A google search will bring up tons of information.
There's even an official Arduino example which demonstrates how to control stepper motors. One day hopefully soon I will make a low-cost controller to suit the low-cost nature of this machine.
One example of a controller which I've built, and which is controlling the machine in the video, is here: