How about Nautilus Battery IV ? Make an opponent force subs to the surface, vice simply waiting for the battery charge to time out.
I like the idea of being able to craft my own versions of prints. This would/could make a HUGE jump in variation in the game, talk about a way to make it different! The ability to combine armors, possibly create your own hull.... This, to me at least, would be a lot of fun, I like being able to dig into the nuts and bolts of things, come up with something nobody else has thought of, that nobody else has! IF this were to be combined with some form of alliance sharing program, so alliances could come up with their own brands of items, and share them in the alliance (leave the alliance, leave your alliance specific builds!) I think this would be a VERY good improvement for the game in general and the alliances in particular!