Ah, this is the answer I was looking for! I've made the template (gabarit). I'm debating how many nails at each end, one or two?

I see Warré suggests using glazier's pins (that is, thin nails without heads) used to secure glass in wooden window frames.

What type of nail do you use? The easiest to hand for me is the type used for assembling frames in conventional hives. They are are 25 mm long, about 1 mm thick and have a 2 - 2.5 mm wide round head. They are coated with a hard lacquer which delays corrosion. I was considering using one of these at each end of the top-bar (latte) without cutting off the head, as they are easy to pull out.

David Heaf

Pays de Galles, UK