A fun, simple way to make a stamp is with adhesive foam pads.

These foam pads are sold as foot cushions for corns, calluses, and bunions.

Some art supply stores also sell sheets of foam material just for the purpose of making stamps.

The advantage of using adhesive foam to make stamps is that there's no carving. You just cut the foam with a pair of scissors and stick it on to a wooden block or a jar lid.

Usually, these foam pads will have a plastic skin over them which resists ink. You will need to peel this skin off of the foam. Use a toothpick or straight pin to stick under the skin and get it started. Then, grab it with your fingers and peel it off.

If the corn pads you buy are labeled as being "soft", then they probably won't have this skin on them. Also, the sheets of foam from the art store do not have this skin.