"Stuff" would be slang for anything you can give me or "give me some stuff and I can do my job better" that being said.."Stuff" can be parts or tools or a lack of description for an object you need or want..(you don't know the name of it, you point and say I need that stuff right there.
I hope that helps..
If you call it 'Stuff' os because you DON't NEED it. If you need something you just say: I need drivewheel, I need an antenna, I need xxxxxx. If you call it 'Stuff' is because you WANT it but don't actually need it.
I know that MATOTOY have some free stuff but I don't actually know how this works. I mean: Can I purchase one bottle of HL Smoke oil and ask for 5 of each free stuff item that they have?
Jose Morais