[duffmancd]

Have you seen the episode of Scrapheap challenge/Junkyard wars where they did just that (in a shed, with a pile of scraps!) [1]? However they made "wet" subs rather than dry, and nothing required to last 2km of travel, which reduces the challenge quite a bit (to say the least).

[1] http://www.the-nerds.org/submarine-design-notes.html