Help with armor/shell pieces

[Angel Bun]

Alrighty, so, I'm a relative newbie to this hobby, I've never done a custom jointed figure before. I have, however, worked on a variety of projects and mediums, including some sculpting and modification. My first custom figures are three Transformers Prime FE Starscreams (Deluxe Class), working towards character accuracy. The other two will become Thundercracker and Skywarp, following my own designs.

Right now, the part I'm most iffy about are the shoulder pieces. While I'm not going to drive myself to the brink of insanity by trying to get it 100% correct, I'd like to get their shoulders looking nice.

The shoulders are basically a stack of thin shells.

What should I use to make these thin shell shoulder pieces?

They need to be thin, but light and strong. Something in plastic would be ideal, but I need to be able to paint and sand it.


Could I try heating up plastic with a heat gun or heated sand/salt, etc, to bend it into shape (with or without a drape mold)? What sort of plastic should I use for this?

Should I try casting the pieces? I know that bubbles can be a problem (pinhole bubbles would be fine, easy enough to fill, but not larger), what sort of casting materials should I use? I'm hoping that there's something simple that doesn't require the use of a vacuum chamber/pressure pot (expensive!)

I've worked with Apoxie Sculpt before, but I think it'll be too heavy for this application and too brittle as well at the thickness I'll be working at.

Remember, I'm working in triplicate! While each outer piece will be slightly different from one another, the main form will be the same.

Any other suggestions are more than welcome!