I agree, interesting.I made a few sailing ships in the bottle. Nothing great,but very challanging. One thing I learned was to not attempt to make everything out of wood, which I was trying to do. I found watch gears made good, small steering helms. Cooper tubing good cannon barrels etc. As far as U boat models, mine are just simple compared to what you all are building. I didn't fully understand that there were working models. My ignorance, but now that I do, I will try to follow some of it. Thank you again for the reply.