One good thing when being around for a bit of time is that you get great help when asking for some very precise stuff. So here is a gentleman that scanned me some very old plans for Whitehead Torpedoes as they were built in Fiume -ex Austria Hungary. Well thanks once more because they're almost finished by now, and reasonably accurate.
The first thing I had to do was to cut some aluminium and brass tubes at the right dimension using this kind of plan
Then actually cut the tubes. i filled them with Green Stuff so that every element would be at the center of it's parent.
Let's cover those assemblings with Magic Sculp, wait for a few days and then sand until the shape is perfect. Now those early torpedoes look so much better than later types.