You can use the top rack of the dishwasher for machine cleaning.  Do not use extra heated wash or extra heated dry.

You can clean your cookie stamp using warm soapy water and a soft brush to get out any flour or sugar in the smaller areas of the stamp.  Air Dry.

If you experience caking of sugar/flour on the stamp – this can happen on a very warm day – you can clean the surface of the stamp with a paper towel, a soft toothbrush or another type of soft brush, and any small pockets or areas with a brush or toothpick.  Do not use any metal or sharp instruments to get the dough out of tight spaces because you may alter or puncture the plastic stamp.