A small screw driver wold be “materials for making an explosive device.” I carry one such for tightening up the screw in the hinge of my glasses. Actually, just about anything can be such materials.
I would assume any set of precision tools could be deemed “bomb making tools” then.
I forget where I read it, but the idea is to make so many rules/laws that it’s impossible to obey them. Thus making everyone a criminal.