Like the router table, my big bench (Kreg frame with maple top) has an open hole underneath that needs to provide some organized storage (a piece of plywood with "stuff" piled willy-nilly on top doesn't count). So I'm going to combine various ideas that I've seen and make some storage. It will have two levels; some full width drawers which open from both sides on the lower and a collection of shallow drawers on the upper level. The upper cabinet will need dadoes cut in the top and bottom for the dividers and I need a way of accurately cutting tight dadoes to suit the Sande plywood I use for shop cabinets. Looking for a quick and easy way to do it, I'm going to combine a couple of ideas - a T-square router guide and a method I just saw (in an old edition of Wood Magazine?). I made the T-square and will take some photos of it in action to explain better.
Checking the assembly for square. I glued wooden edges on the contact faces, hoping that they would hold up better.
Added a brace on the back to stiffen it up. This also give a handy clamping area, just reach across from the outside and clamp the brace and workpiece.
Pocket screws to attach the brace to the beam.
The completed T-square.
How it works. Rather than just guide the base along the edge of the beam, a 1/2" spacer - assuming that a 1/2" bit will be used to cut the 3/4" wide dadoes - is placed against the beam and the first pass made running the edge of the base along the face of the spacer. The second pass is made by removing the 1/2" spacer, adding in a scrap of the material being dadoed into the part, and making a second pass which gives an exact fit to the material. I'm planning to bore a shallow hole, slightly deeper that the depth of the dadoes being cut, in the base, slightly outboard od the wood edge banding. This will give the router bit somewhere to sit when starting the cut, and will also give an exact cut line indicator so all I'll have to do is line up the edge of the groove with my layout mark. This concept works because the router is moved for the second pass by an amount equal to the difference in thickness between the 1/2" spacer and the material being used. The good thing - it will work for different thickness of 3/4" plywood, and the cut line indicator stays in the same position regardless.

Checking the assembly for square. I glued wooden edges on the contact faces, hoping that they would hold up better.

Added a brace on the back to stiffen it up. This also give a handy clamping area, just reach across from the outside and clamp the brace and workpiece.

Pocket screws to attach the brace to the beam.

The completed T-square.
How it works. Rather than just guide the base along the edge of the beam, a 1/2" spacer - assuming that a 1/2" bit will be used to cut the 3/4" wide dadoes - is placed against the beam and the first pass made running the edge of the base along the face of the spacer. The second pass is made by removing the 1/2" spacer, adding in a scrap of the material being dadoed into the part, and making a second pass which gives an exact fit to the material. I'm planning to bore a shallow hole, slightly deeper that the depth of the dadoes being cut, in the base, slightly outboard od the wood edge banding. This will give the router bit somewhere to sit when starting the cut, and will also give an exact cut line indicator so all I'll have to do is line up the edge of the groove with my layout mark. This concept works because the router is moved for the second pass by an amount equal to the difference in thickness between the 1/2" spacer and the material being used. The good thing - it will work for different thickness of 3/4" plywood, and the cut line indicator stays in the same position regardless.