I'm new here but I'll throw my two cents worth in:

You could back them with polymer clay. It's used all the time for jewelry and buttons and can be cured in your oven at home. I don't think I would dry any garment with pc on it though as it might over cure and become brittle. It's inexpensive, comes in a variety of colors and neutrals and it's easy, just follow the instructions on the package.

Deanna

You could always laminate a thin piece of tin or copper to the back face.  Maybe sandwich the stiff backer between two wood buttons.  Sealer by itself might do the trick.

I know, I know! Wood filler!

I'm just thinking about stuff I have on hand. We've got a lot of stuff around here, but I don't think there's any bondo! ;)

I'm not sure if caulk would be too flexible.  If the backing is flexible then the wood could over time loosen aliong the grain lines and fall apart.  Bondo is rigid and would keep the wood from being able to flex along the grain.  Then again, until we try, who knows.

Good idea! Maybe even a coat of caulk on the back....?

I'm thinking that if you put a layer of bondo or such on the back, and coat it all in a sealer, then you probably could make these functional and not just decorative.

Jim