I don't see any problem building a sub from vac form mouldings. Skip Asay's kit's are made this way, and plenty of folk praise them. Also Robbe kits are vac formed, and they also work well.
It's not such a good material to use for a pressure hull though, not as stiff as fibreglass. Also the collision impact resistance will be somewhat lower, but then I don't reckon you'll be slamming it into the side of the lake too often, eh!;)
Most vac formings are moulded from ABS or Styrene.
ABS needs special attention, as not all glues will adhere well to it. Stabilit Express is one glue recommended.
Styrene is easier, epoxy glues work well here, as well as solvent based (Acetone) glues for non stressed areas.
Edited By Sub culture on 1063248124