It moves with transmission by mason cord or packing tape which further lowers the cost.
Very detailed building manual:
GitHub repository with project files:
|QuadRap in first version|
There seams to be two or more different versions, so excuse me if mixing QuadStrap and QuadRap variants ...
If you are interested in different low cost 3d printer with no 3d printed or CNC parts take a look at Delta Twister, it also has very detailed step-by-step building tutorial: