Actually, that's what I had in mind ...
I'm doing the orbiter at 1:72 scale in balsa, using the old Guillow's
kit as a guide. Cockpit, wing leading edges, and OMS pods will be
vacuformed with Monogram orbiter parts acting as molds. I'd intended
to scratch build the tank and boosters too, but wanted to scrounge some
pieces from the Monogram kit ... LOX feedline and fairing, ET thrust
structure, bipod, SRB noses and aft skirts, etc. I may vacuform some
of that too, depending on how the weight plays out.
Anyway, I thought it would be easy to lay hands on one of the Monogram
full stack kits .... it's not. Well, it's not easy AND cheap anyway.
: ) I was able to find a built-up tank and booster set, but it's
been assembled with way too much glue and painted, to boot.
I'll keep looking. Thanks for the suggestions!