D fin templates

There are various historic D fin shapes, but a simple and good one is just a half of the letter 'D' with or without a cutaway. These can be drawn with a compass and a straight edge. The advantage of this planform for a wing or fin is that: " Induced drag is minimized, since lift distribution is near optimum, and because the span efficiency of a planar wing is optimized when maximum span is at the trailing edge. " ( http://www.esotec.org/hbird/HTML/Aero_F.html )