PicoRap tiny printer

Work in progress - X carriage and belt attachments still need to be designed

Tiny purpose-built 3d printer.

Goals:
- Extremely cheap, probably around 40 euro (not including power supply) with 28byj48 extruder, still below 50 euro with Nema 17.
- High quality using MK4duo's backlash compensation
- 50 x 50 x 150 mm build envelope
- Extremely compact < 150 x 100 x 220mm ?
- Easy assembly


Uses 28byj48 steppers, which means this will be a SLOW machine (around 12mm/s?)

Once this mac