Due to Popular DemandI've gotten a lot of questions regarding the construction of my GLaDOS cosplay recently and rather than answer each of them individually, I figure that typing this up is faster.
For the halfmask:
I was heavily inspired by Volpin's Portal Gun tutorial, even though I wasn't making the gun. I tried to follow his process, since I knew that the finished mask had to have the same plastic-y glossy finish. However, Volpin is a crafting genius and used a lot of vague, but still very technical, mumbo-jumbo in his descriptions so I interpreted it as best I could.
Also, the foam carving and the gesso sanding is very messy and will leave dust everywhere. Don't do it indoors! I was stupid and pretty much did this entire project in my bedroom. Everything is still kinda dusty and I probably have cancer or something from breathing it in.
Step one was gathering the materials:
Medium and Fine Grit Sandpaper
Black Acrylic Paint