I built a Queen from the 1986 James Cameron movie ‘Aliens’. The head was built on a base of foamboard insulation, then used sprayfoam insulation for shapes.
The front incorporates a plastic skull from a costume shop, and I used black plastic to make the shiny skin of the head itself and spray painted the rest black.
The body was built on an old army backpack frame. PVC and cardboard, then liberal amounts of sprayfoam applied atop that.
The tail was made from 1/2″ PVC with foam pipe insulation making the spines. Spray foam insulation helped make it organic looking.
The legs and arm plates were sprayfoam on cardboard, cut off the excess cardboard, then painted black.
It worked out great, and was very well received. I also won the costume contest at work!