After sizing the stock for the handles and blades, the trickiest procedure was cutting the slot mortise in the handle. To make the cuts safely I made a sliding tenon jig that rides on my tablesaw fence (shown here).

I made cardboard templates for the handle and blade profiles, and then cut them with the band saw.

Here are the finished parts. I used persimmon for the blades and two of the handles and cherry for the other two handles. Persimmon is very hard (only North American wood that is in the ebony family).

I used a small steel square during glueup, positioned on the inside of the handle and blade, to keep the corner bridle joint square while I pinned the pieces together with 23 gauge nailer. After the glue dried, I used my shooting board to square up the top side of the blade.

I used my framing square to check for square. With the parts held against the light any irregularities can be easily seen.

The inside square was trued up using my scrapper and fine sandpaper and checked with the framing square.

Here are the four finished TrySquares. The cherry handles make for a nice contrast with the lighter persimmon blades. The persimmon, when sanded, had a 'soapy' feel since it is so hard and smooth. I impregnated the knot at the bottom of one of the persimmon handles with marine epoxy to stabilize it. Yes, I kept the knot on purpose, I think it adds character.