These flexible filament feet fits the bottom on this printer: http://www.thingiverse.com/thing:273890 The T-slot extrusion are made for M8 bolts, all you need to do is to thread the inside of the extrusion, print the feet in flex (or what fits your need), and stuff an 20mm M8 bolt through the feet up into the extrusion. If printed in flex you need to make sure the M8 runs smoothly in the extrusion, before trying to screw it in, as the bolt-head will not hold it tightly. Print in flexible filament - Any type should do. I did 15% infill 3 top and bottom layer, 2 perimeters Use M8 20mm with a hex-head (hex.outside-head). Tap and thread T-slot extrusion. Clean and make sure it runs smoothly. Screw in feet with hand until tight.