on a small scale it wouldnt be an issue. sure, if i started producing them, then YES. but ive worked in shops and never had a need for homemade ones. also, since ive started building skis with inserts, a good jig may come in real handy, so i may just construct one/some.
and also, if its just a one time mounting deal for real fatties or something, just use a real fine point drafting marker, and a good ruler. its possible to mount bindings VERY true in about an hours time with just a marker, a ruler, the bindings and the boots. specially on skis with easy and nondirect forward pressure settings.