does anyone know a good safe way to dissolve potting compound without damaging the components?
It depends on the potting compound. For instance you could probably use any number of common waxes and just melt them off... Other common potting compounds are really inert, and or get very similar to the materials chips are packaged in (silicone, epoxy.)
I've been wanting to build electronics into PET pre-forms.
Tough as nails, cheap, designed to be gas and water-tight, and neat-looking. Unfortunately, I haven't found a good source of low to moderate quantities in the desirable range of sizes...