There are a variety of construction techniques for use with waterjet or laser cut parts. We have profiled a few of them elsewhere on the website.
We've made the pieces in acrylic here so you can see how it all fits together.
Here's how this as yet unnamed technique works. One piece is placed perpendicularly to two pieces whose faces run in parallel. The perpendicular piece has tabs which match slots on the other two pieces. Unlike in the t-nut technique, the perpendicular member is not bolted to the other two pieces. It is instead held in place by compression. The two parallel pieces provide the compression by being held together with long bolts.
This technique lets you use larger bolts than tab and slot for greater strength. The tabbed piece is also free to have other features on it without you having to worry about the location of the fasteners.
We don't have a name for this construction technique yet. I feel it's very useful to give these things a name so we have a convenient shorthand to refer to when building this way. Any suggestions for a name? Let me know.