Yeah, it's mostly a matter of just getting really comfortable with the Pen tool. I use Bezier splines almost constantly at work, so it's really natural to me.

The fuel tank also wraps over the top of the ship. It carries 30 "tons" of fuel, but Traveller tons are not equivalent to real-world tons. 1 ton = 14 cubic meters, and the volume shown accounts for about 20 tons.

Little information is given in the base rulebooks concerning the power plant, but it does say that the fuel is typically hydrogen, which leads me to believe that the ships are fusion powered.