I made these as a way to quickly detach the foam pads for cleaning or switching to the PU-leather ones via magnetic connection with the screws on the HD681 Evo Headphones.

I used 4-5 tiny 6x1mm magnets per hole that fit the Screwholes. (as in the 2. Picture) you might need to heat them up with a lighter to fuse with the PLA. The Method is not Perfect but it worked for me for over a year so far. I might fix it once i find time and motivation.