Coffee plastic

this recipe I found on youtube and I wanted to test. In this recipe I use 20ml glyerol, 60ml water, 10gr coffee, 1/2 lemon and 40gr corn starch. I mixed all this and brought it to the boil. once it boils, it forms a thick knit that is spreadable. I have spread this knit over a baking sheet and made a shape with it. Normally this should form a hard bioplastic after dehydration. so far no success.

Isnt typically the glycerol to maizena ratio much higher, like at least 1:1 and no water? best of luck