Oh that's great!, I'm glad I helped
Fabric+cardboard does work, though it's not as fancy as leather and metal... or halogen lamps, that's a great idea!
Aw, I wish I had a second-hand shop nearby! But I do have some leather, so right now I'm working on some leather goggles too
Mmmm, why don't you just apply a very thin layer of paint? Or you could put some black paper(or napkins) on the inside of the goggles?