I got a cheap storage rack ("Muscle Rack" brand) and realized the legs were going to scratch my laminate flooring to death. Just threw together a bit of openscad to make feet for them to stop scratches and maybe add a tiny bit of stability on hard surfaces. Works great when printed in flexible filament.
It's customizable to any rack that uses an L-shaped steel rail. Default size is for the cheap muscle brand rack I got (1.25" on each side). I used about 1mm tolerance on the length of the slot and 0.5mm for the slot width, doesn't need to be too loose or snug.
No need for fine layers here. Use a high infill to make it not squishy. Might work with ninjaflex (but could be too flexible, haven't tried yet), semiflex or generic tpu works great (I used makergeeks maker flex which is about as rigid as semiflex).
I doubt this would work well with rigid filament, but if it does please leave a comment about it.