One I always see that confuses people is Plastic card, plasticard, Polystyrene plastic, styrene sheet plastic... All the same material but depending on location called different names.
Common Manufacturers' of sheet, strip, rod, tubing,textured sheets..
Other sculpting Materials/puttys
Brown Stuff - is the brown version of Kneedatite. Cures very hard
Magic Sculpt a hard curing Epoxy putty for sculpting.
Avies Apoxie Sculpt a hard curing Epoxy Putty for sculpting, certified Non toxic so they claim.