I designed these to go on my print of RoboHut's excellent guitar volume pedal:
https://www.thingiverse.com/thing:4875203
Really, though, little feet like these are generally useful if you're able to print in TPU or TPE. I'm sure durable feet can be bought pretty cheaply in bulk online, but where's the fun in that?
The author marked this model as their own original creation.