Hi there! I was also interested in constructing this costume. I have a bunch of HQ screens from the latest episode that features the Commandoes in better lighting. I've already started to source some soft parts, and I have a SO that is big into prop making that will help me construct some prototypes out of worbla.
Consequently, we were also thinking worbla would work better in general due to the easier to sculpt nature of it and ability to worked with better to create the more seamless contacts or even completely seamless (something much harder to do with ABS, fiberglass, etc.)
But I'm in the same boat as you -- no idea what I'm doing!