Equipment straps

Lead foil is a good material as Hasen has already said. Wire can be formed into buckle by wrapping around a square form of some kind. If you can chase down a copy of Shep Paine's old book "Modeling Tanks and Military Vehicles" (isbn: 0-89024-045-0), he has a lot of tips and rudimentary "how to's" for vehicle stowage in it.

I've used the lead wrapper on the tops of wine bottles for this purpose plenty of times. It's very easy to cut to size and work into the position you want.