styrofoam (polystyrene) dissolves in acetone or limonene. Limonene is a terpene product derived from citrus oils so it's pretty "natural" The dissolved plastic can be painted onto unfinished wood to waterproof and preserve it.
note: I don't know if this finish is food safe or how durable it is. I'd also like to try different plastics
86944 wrote
Sounds flammable.