I use plastic tiles for my garage floor (NB: love 'em, pricey, but not more than paying someone to epoxy it) and I wanted to protect them from the sharp edges of a metal shelf. I did not look here first for "shelf feet," I just threw these together. There are other perfectly nice shelf feet also out there :)

These are to be printed solid. They're sized partly to take more weight from the shelf, and partly because I wanted to use "lighten". The grey PLA was a throwaway color I used to test, but it matched well enough that I printed all 4 corners with it.

Bonus, I have a similar problem with jackstands; the larger feet fit under corners of two brands of jackstand (which are suspiciously identical to one another in design). They work GREAT, as pictured.

UPDATE: after a few weeks of sitting under loaded jackstands: 100% infill shows NO deformation, and 33% infill shows a little crushing but nothing to prevent their use.

Prusa

i3 MK3

Doesn't Matter

Doesn't Matter

0.15

100%

These will be taking load, so use very dense infill. I found my slicer & printer seem happiest if I set it up for lots of bottom layers (like 20), rather than have it try to fill in a very dense infill pattern.