(Below) Beginning to piece it all together. All of the numerous poly pieces were fixed to a thin plywood cube. Because solvents will destroy polystyrene foam, it's important to use the correct adhesive.
It was into this cube that Tony would place his head. There's a hole cut in the cube, where the mouth is.
I stretched black net curtain across the mouth, so that Tony could see out, but nobody could see in.
The yellow lumps are just poly spheres, cut in half. Once all the main facial features - Eyes, mouth, nose - were in place, the gaps in between were filled in with more sculpted poly shapes. Once finished, the entire mask was covered in another layer of varnish.
Remember when I said solvents will destroy polystyrene? Well, in my wisdom I'd bought a spray can of varnish. Mostly for speed of use. Only, it turned out to be a solvent-based varnish, unlike the water-based varnish
I had been using previously.
Luckily, the paint protected most of the mask, but here and there it ate away at the unpainted poly in seconds.
In my defence, the people in the shop told me it would be fine. But it's really important to check so you don't destroy your work.
I was able to patch up the damage pretty quickly, which wasn't too bad. It could have been so much worse.