I don't like the cork idea. YOu need to keep the retainers on the stud and that's not going to leave much of the stud to stick into the cork. I've only got one earing and I never take it out overnight but if I had a lot I would use a piece of punched metal. That's metal that's used for screen, or venting that has lots of 1/8" holes punched in a pattern. I'd take a piece about 4" x 8' and slot a piece of wood so that the metal stands up in the wood base. Spray the metal black or your favorite color and insert the studs thru the metal and put the retainers on them. That way they are all there to pick from, no chance of loosing the retainers and they aren't going to fall out. You can find the metal at a hardware store and it's easy to cut.