Is it a punch or a stencil cutout and hotcut process. Im very interested.. looks nice and clean!
This is how I do the Leading Edges:
1) Cut and fold a strip of Dacron (Spinnaker in this case).
2) Fold 5cm back and cut a small triangle from the last 5cm at both sides. I mean the part that would stick out when folded back and folded in length if you don't cut it (just try). Sorry, English is not my motherlanguage. I had a bad grade in highschool
3) Now glue the strip to the back of the kite, starting at the wingtip. Just make sure the sail is exactly touching the fold. I do not tape the Dacron to the A0-plan or something like that.
4) Use a pencil to mark the place of the cutouts (they are on the sail already in my case, I did that when glueing the sailhalfs).
5) Now find yourself a soldering iron with a sharp point (see below, at the bottom my other soldering iron) and a piece of metal with a hole in it with a size of 12mm (10mm was too small, maybe 14mm is needed with thicker rods). I found it in DIY-shop, I think it is used in plumbing. I tried this with cardboard, but that doesn't work!
6) Cut the holes 1 à 2 mm from the fold in the Dacron. Closer: the hole will wear, further: there will be an ugly bend in your leading edge. WARNING: be very careful with a big sail and a sizzling hot iron on one table! Especially when you move the sail. (Yes, I had a small accident once. That set me back in focus for the builds after that.)
7) Glue the Dacron flat and stitch it.
Maybe some of the steps are unnecessary to explain, but now it is a complete instruction.
Now off to the plumbing store!