Sometimes all you need is a little sandpaper ...
... and a lot of patience.
Here is a little something I made to go with my 1/144 Japanese Betty torpedo bomber display, a Type 91 Mod 2 aerial torpedo and trolley. I'm pleased with the way this turned out. The real deal was not quite 18-inches in diameter, 18-feet long and weighed 1,840 pounds. Scaled down to 1/144 that's about 0.12-inches by 1.5-inches. A piece of sprue of suitable diameter was cut to length and then the back third was sanded down to get the tapered tail, while the nose was rounded off. A grainy black and white photo provided enough details to bash out a trolley with scrap plastic and my Waldron miniature punch-and-die sets. And no, it's not completely accurate - the Type 91 had eight fins in three different styles on the back end. I thought I was doing really well to get four glued on more or less square. But it does have the two brass props on the end!