This is the die we had made to cut our coasters into circles. The die is basically a strong but flexible steel blade embedded into a block of wood. Our circle die was made with a 3 1/2 inch diameter, but dies can be made in almost any shape or size you want - depending on your die-maker. When calling to order a die for a platen press, make sure to tell them to make it "type high" or .918 inches. The die gets locked up in the chase the same way as a base when printing. We put a piece of sheet metal on the tympan paper to protect the platen from the sharp blade. The pink rubber squares are there to push the paper (or coaster) back away after each cut is made.
We learned how to print on coasters and cut with a die from Susan Angebranndt at the San Francisco Center for the Book. Susan is an amazing letterpress printer and a very patient teacher. She runs Green Chair Press and has a very smart blog about her work with letterpress, type, book arts and all sorts of "ephemera," as she puts it. If you are anywhere near Northern California, I would highly recommend taking a class or workshop at the SFCB.
