This also works with bars of shampoo. And bottle caps are so diverse: different places, different drinks, different brands…….
(re-post)
A magnetic paper holder (the kind that is meant to go on a fridge), a bottle cap; press bottle cap into soap…….
……. clip paper holder onto towel rack over sink…. introduce bottle cap to magnet …. dah dah …..
Soap drips into sink, dries between uses.
It can also be clipped to the faucet handle in the tub.