Found Dovetail Template

For those who asked, here are the details of the template I found in the red plastic box. The wood's mahogany and it seems to have worked fine for around eight decades, my guestimate is. It's a single piece, not laminated, but you could laminate it for ease, even with transverse pieces for the stops.

What's nice about this is the perfection of the surfaces on either side/face. Very nicely executed, parallel, even thickness, flat surfaces too. Also, the shoulders are sawn down to depth with a superthin western saw, maybe 1/64".