Options for decorating dulcimers

Diamond shaped sound holes: If you do not like heart-shaped soundholes, you can easily change them into a diamond by doing some careful cutting with an exacto knife. Put scrap cardboard below your soundbox so you can cut through all the way, and expect to make several passes with the knife.

I know some teachers have had student make their own stencils to stencil designs on dulcimers, and others have used stickers and decoupage. Those with expeience, please share specific tips for doing this!