Very nice model. It makes me want to print this one up and start it. The shrink tubing idea got me thinking so I checked my favorite source for stuff, American Science and Surplus and found this:
http://www.sciplus.com/singleItem.cfm/terms/8801
It looks like the kind of thing that might just work. And just today I found air-dry modeling clay at WalMart in their hobby section.
Potential sources for modeling folks on this side of the pond.
Cecil