I assume you're familiar with the "fluke sandwich" using powermesh to secure the silicone to lexan or whatever monofin you're using? If not, that method's fairly simple...cover the foot pocket region with saran wrap, then use poly zap (for lexan) or some other appropriate glue to secure fabric to the fin. Pearlie suggested crumpling the fabric a little to give the silicone something to grab, but I found that made my fin lumpy (I probably overdid it) and I ended up with some air pockets inside my fluke. Make sure the saran covers anything that will inhibit silicone (especially if you are using a commercial monofin with rubber foot pockets), and try to squeeze out all the air pockets before the silicone cures completely. I got a few out by piercing them with pins afterward, but when I try this again I'll just use a flat sheet of power mesh. Don't forget to leave drainage holes! (I used big popsicle sticks wrapped in saran wrap. Mistake! Nearly impossible to remove afterwards.)
When I made my duct tape dummy, I created it all the way down to the heels. That gave me a good idea how long to make the body. I already deleted the few pics I took, but basically once the fluke was complete, and the body was complete, I put both on and took pics of the missing portion of the ankle region with toes pointed and flexed. I used those pics as a guide to determine how many scales were needed to reach across the divide. Then I built up, adding scales from the fluke to the ankle region. I did the dorsal side first so I could add in another couple of layers of power mesh over the heel join inside while I could still reach it. I didn't bother to reinforce the ventral (top of ankles) join, figuring that region gets less stress. Don't forget to stick in something into the body to keep the front and back halves of the ankle region from getting accidentally glued together since you don't have a dummy behind them (I used a magazine covered in saran wrap).
There was quite a lot of luck involved in this whole process...I'm very happy I judged the distance right the first time. :)
OH! And I should mention that I drew a vertical line all down my dummy in the front and back in black sharpie, so I knew exactly where the center line was as I was pinning scales. By the time I glued the scales down it was pretty clear where the center line was, but that's really important to do!
