I don't think it would be that difficult iceonaboy. I've made a few posts on another thread here
http://models.rokket.biz/index.php?topic=797.0 and this one I've got the parts printed off, but unfortunately on portrait mode, not landscape so I have a bit of extra work to get them to fit right.
You print the parts on card stock, which is thicker and stronger than ordinary typing paper. And then there's a framework of bulkheads and longitudinal stiffeners inside to give it shape and provide a large enough surface area to glue the deck and hull plating to.
I've built 4 paper airplane models using this method, and once they're finished they're surprisingly strong. I'm pretty sure if I could find a lightweight motor and battery, I could make them into RC and they'd fly reasonably well. I've been downloading paper model kits and now have maybe as many as 200 on disk, everything from tanks and halftracks to sailing ships, battleships and RMS Titanic. There's also these two U-boats of course, and about 50 WWI aircraft and about the same number of WWII planes.
The specifics construction details of the paper model presented here by Subfan is different than the one I posted, but the basics are similar. Subfan's model here is an early version, with the netcutter and deck gun, while mine is the U-999 at Luboe, Germany, with the schnorkel, but both models have some really interesting detail.
I've been researching paper model construction methods, and for ships and U-boats, they recommend painting/spraying them with a coat of varnish or urethane when finished, and with some ballast, they should be able to even float, although I wouldn't trust them to stay dry for very long.
