This is the bioplastic recipe using:
7 parts water
1 part vinegar
1/2 part glycerine
1 1/2 parts starch
Here I poured it in thick circle molds, not sure how it’s going to dry - seems to be like dried hair gel so far. But some people say it should be dried for a few days. I tried adding in some soot as a pigment but it didn’t separate very much in the liquid, hence the speckles.