Rotozip sells template kits for making kitchen trivets. Their design is suggested for ceramic tile or exotic woods. The kit includes plans for building a jig to assist in the cutting operations, a bunch of patterns to get you started, and it sells for about $10 at the Borgs.(slang for the big box stores like HD and Lowes) Once you get the hang of making these it's a small step to designing your own. You dont need a Rotozip to make these, just an 1/8" bit to fit your router.