I hand sculpted a weird little 4 inch by 4 inch relief sculpture of skulls, made a mold of it, cast it in SmoothCast 65D from Smooth On, paint it up, submerged the sucker in a beverage coaster mold, then cover it in a self leveling, water and heat resistant epoxy resin.
Personally, I think they came out pretty bad ass!
Please remember, each one is handmade and hand painted, so they may look slightly different from the pictures, and there may be a bubble here and there, but I do, in fact, painstakingly make each one myself and try my best to make them as awesome as humanly possible.
Each one has a signed cork backing, so it won't scratch your table and they are approximately 4 inches square by about a 3/25 inch thick.
Coasters are sold individually, if you want a set, you much purchase them separately.