The system is made to switch back and forth between 3d-printing and milling as fast as possible. It consists of the holder for the proxxon flexishaft micromot 110/P (can be attached to a dremel too) and an attachable z-axis pushdown system. The problem with the Prusa i3 is that the z-axis loosely sits on the m5-nuts and only moves down through it's own weight. To mill and especially drill pcb's for example some more force is needed. The pushdown-system can easily be attached without demounting the axis. Two lm8uu's are needed! http://www.proxtools.com/store/pc/viewPrd.asp?idproduct=35 Can be used to mill and drill printed circuit boards for example. Work in progress, more coming soon!! Update: Project closed, the design of the Prusa i3 with it's x-axis just laying on the nuts on the z-axis is simply not suitable for such precise milling. You can use it for drilling as it worked for me too but precision on the z-axis when forcing it to go down is just not high enough. Print: