A new era of peace meant that Bruno had more time to plan for the war effort. His first shipyard was up and running and was beginning to work on the blueprints he had previously designed for the type XXI U-boats.
Quite frankly, the means to manufacture all the components of the Type XXI Submarine, or the improved variation of it which Bruno designed, already existed in the era. Diesel Engines were invented as far back as 1893. While Electric motor-generators were designed first in 1831. As for alkaline batteries, they were a recent invention having been first created in 1899.
As for the Hull itself, it was actually easier to manufacture than, say, the recently launched SM U-1 U-Boat by the German Navy. And the reason being is that unlike U-boats of the current era, the Type XXI was manufactured quickly via prefabricated sections welded together.
