Do-It-Yourself Rubber Stamp Project
13. Put the napkin(s) (or tissue paper) under a piece of paper.
The center of the napkin should be under the paper exactly where you plan to use your rubber stamp. The napkin will help the rubber stamp to "fill in" wide parts of the foam and whatever part of the design is in the middle of the bottle cap. Without the napkin(s), the middle of large pieces of foam, and the middle of the bottle cap, would make no mark or only very light marks on the paper.