The "Postage Due" stamp set is a great collage stamp and I really like the finished effect to create these rustic coasters.
I have stamped the image using Staz-on Jet Black onto some stone tiles that I purchased from my local Bunnings store. The stone tiles do have holes in them but I really love the rustic effect that this gives the finished coaster. The finished coasters are 4" x 4".
I sealed the stone tiles with Mod Podge before stamping the image and then put two coats of Mod Podge over the top to seal it. An acrylic sealer can also be added if desired. A piece of cork was adhered to the bottom of the tile.