we bought a box of these tiles from Lowe's
But they come REALLY dirty. So you have to wash them thoroughly
Wal-Mart or Target sells these cork liners.
I cut them to fit the size of the tiles.
used a corner rounder to round the corners.
Then I put the cork liner on the back of the tile.
Finally you put a Vodka Soda on it and enjoy the new coaster! :)