Found this brass and enamel item at the chip show at the Palms last week. Uniface, with a felt pad on the reverse, it's apparently part of a set of coasters from Stardust years ago. It was cheap. Size is 75 mm in diameter, and weighs about a quarter pound.

Others from the set (5,000 and 10,000 I believe) offered by another dealer and with the felt removed were not cheap and I didn't bite [g].