OK, so after re-marking the foamcore I started cutting it out.
Nerve compression in my neck plus tendinitis = Exacto Knife not a good idea.
Stopped and got a nice ergonomic-handled utilitly knife.
Carved out 9 main arc segments and 9 trim arcs.
Today, thanks to 3M Super77, they're all laminated together properly.
Next step: Paint!
First: A layer of Rust-Oleum primer for plastic, so the styrofoam core won't melt.
Second: Rust-Oleum Grey Hammered Metal Finish paint
Then we have to carve out the wells for the plasma disks...