I assumed they would have to be made, that's why I gave some technical information on how they operate. But I did have a slight hope that somebody supplied them.

I suspect 2' is about the maximum size you could manage without having to incorporate the arcs for support. The extra foot of length would make a huge difference too.

I doubt they have been used very much since the 16th century...

2 feet would be a handy size for marking off timbers and laying out joinery, but I am afraid it would be too small for laying out a building plan