Template and Top (front)
I looked at several real mandolins, and made a couple of decisions about the design: the shape of the mandolins would be closer to a guitar than to a lute, and the top and bottom would be parallel to each other.
Then I made a jig for forming the sides, which would also function as the template for marking the shape of the top on a piece of plywood. The jig consists of two thicknesses of heavy particle-board shelving. I cut two corners at 45 degrees so that I'd have correctly-angled surfaces onto which which clamps could bear. I cut a channel in the jig where the neck of the mandolin was to join the body, so I could also use the jig for asssembly. In use, the jig would stand on a sheet of glass formerly used as a glass shelf, to provide an absolutely flat surface to work from. The two strips running along the jig serve to hold it clear of the glass, so that it cannot get glued down by accident.
the jig, on end
Once I'd made the jig, I could move into production. But the jig turned out to be the bottleneck: I could make all 8 necks and pegheads etc. in batch mode, but each mandolin's top and bottom had to be created in sequence.
Before marking and cutting and assembling each top and bottom, I stained and lightly varnished the plywood, using water-based varnish.
If I hadn't done that, any drops of glue getting onto the surface would have soaked into the surface and prevented stain from having any effect - giving a lighter patch. Also, applying varnish reduced the splintering that the scroll saw made at the edge of the cut. For the same reason, I cut the tops slightly oversize and then, after assembly, sanded them to the correct size on a bench sander.