Re: Concept to Completion - Diary of a Sculpt
I should think that one kind of fiberglass is as safe as another except for a breathing hazard of the fine stuff.
Looking at my shelves of several brands of polyurethane, I can see on none of them instructions to "shake" the product. Only one of the two parts needs to be "stired".
Most problems can be ignored. The more difficult ones can be slept through!