Here are three different gauges I have used. The top two use pins.

Here are the parts for the one in Fine Woodworking. The fence was made by cutting a single piece of stock into 3 sections, and then regluing to create an absoluting square mortise for the bar, while retaining the original grain orientation. The bar is then made to exactly fit the mortise. A mortise is made in the bar to accept the cutter (made from old sabre saw blade) and the wedge. A threaded insert in the fence allows a brass thumbscrew to exert pressure on oak plug to hold the bar in place. The spear point bevel on the cutter does not wander and works like a charm.

Here are three different gauges I made using the 'Fine Woodworking' April 2010 design.

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.