About this 3D model
I wrote this little headache-style OpenSCAD because I didn't have the right springs but a few ones from these: http://reprapworld.com/?products_details&products_id=228&cPath=1591_1618 (9 coils of 1mm wire diameter for a total lenght of 25mm with an 10mm OD and 8mm, ID) Bearings were also an issue, the only ones I had where some scavenged from old milling cutting tools (5x9.5x3.2 or something like).