Ezy Mount makes using cling mount stamps a breeze. A good description of how to add cling mount to your unmounted stamps can be found here http://rubberstamping.about.com/od/supplies/p/MountingFoam.htm

There are various manufacturers and brand names available. Ezy Mount for Unmounted Stamps is a must for great stamping of unmounted stamps. The stamp has stability when placed onto an acrylic block. Images stamp crisply. To clean gently use a damp cloth.