This is what one of my cabinets looked like with all of the shell cases for the wood mount stamps. I decided to change most of them over to clear mount, and am sharing the process.
Here is your basic wood-mounted stamp. You can see the layers--rubber, foam, wood.
CAREFULLY peel the foam and rubber from the wood. You want to do this slowly and carefully. Occasionally the rubber will rip or separate from the rubber. However, in all the stamp sets I've unmounted so far, I have only ripped 3, and they have been repairable.
Here is what you will have after you are finished separating the foam from the rubber. Place the rubber side down on a flat surface. Any ideas on what to do with all of the sticky wood blocks?
Next, and also very carefully, peel the sticker from the front of the wood block.
Lay it on top of the foam. You may want to flip the stamp over and align the sticker image with the rubber image.
Trim off the excess.
Add a thin layer of Tombow Mono Multi Liquid Glue.
Let the glue dry overnight.
When dry, the stamp will be tacky and stick to a clear block. I am still deep in the process of unmounting the stamps!