Acetate
I've seen the term acetate used in reference to a number of different materials. But for our purposes it refers to a hard, plastic-like material used in some cases for the sculpting of toys. For the most part, only one sculptor frequently used by Kenner during the vintage era worked in this material-- most worked in wax, a much more malleable and forgiving medium.
All of the acetate I've seen is pinkish tan in color, and it's all extremely hard and heavy. The sculptor working in this material, using a variety of manual and mechanical techniques, needed to be incredibly precise-- since mistakes could not, as they could with wax, be easily covered up, a simple slip of the hand might ruin many hours of hard work.
Most acetate sculptings were fashioned in numerous parts, which could then be assembled to make a complete whole. Although one would assume that the hard material would be most amenable to working on pieces that by nature have tight lines and mechanical details, I've seen it used on everything from smaller action figures, to large size and Micro Collection figures.
See also:
Acetate Sculpting for Large Size C-3PO Figure
Acetate Sculpting for General Madine Action Figure
Acetate Sculpting for Unproduced Micro Collection Power Droid
Description: Ron Salvatore