About twenty years ago my son turned up with a plastic bag containing the remains of a model submarine, which was approximately 36 inches long. It had been made of balsa, plaster, and tinplate, which had been heavily lacquered. He had bought it at an auction for £20.00 having decided that his Dad would be able to mend it, so I was committed to attempt it!
Whoever made it clearly knew something about 'Boats' as it looked very much like a German type IX. It had originally been powered by elastic driving a large single screw and had large out of scale hydroplanes. This indicates that it would be capable of diving and then surfacing at the end of it's run due to a slightly positive buoyancy.
I decided to re-build it using as much of the original as possible, but, by adding exterior ballast tanks, to make everything above the waterline appear like a late war type VIIc so I could add some A/A weapons as they were fitted with these extra arms at that time.
Nothing is claimed to be to scale and weapons, scopes etc are made from junk. Old biro's, bit's of tube and wire, clock and watch part's and so on. The casing repairs were made with skin ply which was difficult as the whole was very fragile. The weapons were made from imagination and whatever was at hand.
Like some of my other models I will occasionally give it a re-fit and add extra bit's as I find something useful, so it's always ongoing. However in the past I managed to sell enough model ships to enable me to buy a small boat of my own which I lived on and so got my foot on the boat property ladder.
Anyway I'll try and attach a series of pic's to show how it slowly progressed. I make no claim to have the skills of Swerge or Panzer3 and other model makers, but it keeps me happy.