One of the many interesting things gleemed from our interview with former Mego Designer Tory Mucaro was that he used to take things home as treats for his then girlfriend. Above is just such an example, a hand made Twiki Production sample.
According to Tory this figure is a urethane resin casting pulled from RTV rubber molds (similiar to how custom Resin heads are produced now). The original models were most likely sculpted by Bill Lemon or Ray Meyers in acetate, a very easy to carve plastic that was available in very thick slabs back then. It was a sort of pinkish tan color and could be polished very smooth, while still retaining amazing detail. The parts were solid and would be set up in RTV Silicone rubber to create molds into which was poured a liquid urethane plastic that would harden in about an hour.
The urethane parts would then be removed from the molds and painted and assembled for sales samples, the original acetate sculpts would then be sent to the factory to be used for tooling patterns to make the production molds. These samples were most likely done at HMS or Paramount in PA as the Mego model shop was very small and limited by its location on the 36th floor in 41 Madison Ave. A good portion of the model work was farmed out to freelance model shops, and these samples are no exception.
Thanks to Tory Mucaro for the pictures and description.