Playdoh preservation - baking? air dry? shellac?

[happytxchick]

Does anyone have any experience preserving children's Playdoh creations? HOW DID YOU DO IT? I read a little online, but want feedback from my BYC buddies.

Should I bake, or will that increase cracking? What temp and length of time should I use?

Should I just let it air-dry?

Should I shellac it afterwards?

Thanks!