: Did anyone ever do this? What are the drawbacks? Should I just go
: with PVC?

I've built 3 non-folding aluminum / ply kayaks. On the one pictured below, I used 3/4" (6061-T6) X .037 wall tubing
which saved several pounds vs .049 wall that I use on folders. The cross sections are 1/2" plywood and the skin is sewn nylon coated with
hypalon. The frame is lashed.

PVC is best used on a folding kayak as the skin can be folded and stored without damage. On a non-folder, sewn nylon or Polyester is a better choice.

This 16 + footer weighs 25lbs. The only disadvantage of aluminum may be the cost vs wood. With no ripping, sanding, or finishing, aluminum
is a viable alternative, and in fact is my favorite method of building an SOF ... but that's just me :)

However, it's hard to beat wood for it's esthetic value. Then again, once skinned, there is little visual difference. Plus, the round aluminum tubes
conform perfectly to the skin.

Have fun,

Tom