At a sign company I worked at years ago they formed acrylic all the time, making pan faces 3d letters etc. It's just the machine used -- this one was big able to accept 12 foot long sheets. It comes down to proper (and even) heating and larger holes (16th to 1/8th dia) in the moulds to draw things in tight to corners etc. I think the max (if I remember right) was 3/16" sheets -- typical was 1/8th". So it is possible.
I would imagine they used something in the 1/16th inch or thinner range for the trooper eyes -- again it comes down to tracking the proper color/shade plastic and finding the manufacturer, then just see what thickness' are/were available. Too bad we don't have access to the LFL and related contractors invoice files!
Doug