I recently printed the huge bathtub submarine by Skimbal (http://www.thingiverse.com/thing:6432) and wondered that no one has created the missing details.
So I decided to do it.
In this download you will find the FWD and AFT divepanels / rudder, the propeller, the periscopes and the cannons.
You will need a bit of glue and little sanding.
U-Boot-Ruder-FWD.stl goes left and right in the 3 holes in the front of the hull.
Print 2 U-Boot-Propeller.stl and U-Boot-Ruder-AFT-Dive.stl (maybe suport needed (45Â° overhang)). use 3mm filament as propeller-axles, and stick it to the slots/holes in the back of your boat.
The Guns may be printed in one piece with support; ( Files U-Boat_0-Gun_Complete.stl / U-Boat_2-GunSmall-Complete.stl), but I think its an easier to print it flat. I have included sliced stl's in the zip, so you can print it flat and glue it together.
The same goes for the Periscope / Antenna.
At least i created a nice Stand for the boat. Print 2x U-Boot-Stand-1.stl and 2x U-Boot-Stand-2.stl and stick / glue it together.