Originally Posted by
Superorb
Bad idea. The best coasters are the stone ones that absorb the condensation. Otherwise, you'll have puddles and the card coasters will stick to the bottom of the cup and you'll end up wearing that puddle.
Yeah, the point of coasters is to protect the underlying table from moisture, but moisture will slide right off the slick plastic of the cards and spill onto the table anyway. Maybe you could use the cards as a base and glue felt to either side of them. The plastic in the middle would keep the moisture from soaking through the felt and getting to the table.