Frank Erskine wrote:

Of course, not all 'plastic' stuff is oil-based - think bakelite.

Casein, oops! Derived from milk, the eco-loonies don't like that.
Cellulose
Nitrocellulose
Cellulose Acetate Butyrate (CAB)
Rubber (incl vulcanised and chlorinated)

And I'm sure there are many more. Mostly however they tend to be crap.
Would people really want to have highly flammable/exploding knife
handles in their kitchen for example? stares in cutlery drawer at
collection of "bone"[1] handled knives Umm other than me, that is.




[1] nitrocellulose.