Im am planning to building my own in the next few weeks or so just havent decided on the design. I wanted 2 collums of systainer storage and a skinnier 3rd for my CT MIDI. One side would have 12” deep drawer trays for the systainers and the back may add more sys storage or drawers for most common used tools. I also wanted the section dividers facing out to have a 1.5 - 2” hardwood edge banding of sorts with domino holes for holding up panels during edge banding like that if Timothy Wilmots benches. Problem i keeping comming accross is the t-lock vs sys3 non-unit size heights. Im going bonkers atm.
I did mine with 20" deep drawers. This leaves some space behind the Systainer for accessories or consumables that go with, but do not fit in the Systainer itself. Mine are just flat slabs with a back stop strip to keep the Systainer from moving and a vertical wall to keep the extras from falling off of the back.
I also did the Domino slots for vertical panel holding, but only on the legs of the assembly bench. I did all 3 legs of the side I use the most. I moved the top off-center to be flush with that side and increased the overhang on the other side.
The biggest headache, as you describe, is the spacing situation. This was all designed around the 32mm system and the 5 sizes of T-Loc. So far, I only have one Sys3 and it threw a wrench in immediately. I had to move one pair of drawer guides down to fit the RO125 into the column. This is actually below the last hole in the 32mm and barely fits.
The
system was fine, before they broke it. Whoever engineered the first 5 sizes with a specific pattern must be very annoyed.