I've learned that you can never have enough cabinet space. I started with a modest rack cabinet design and quickly outgrew it. I expanded it and still outgrew it, although I am using it as a side cabinet in this photo.
As the number of modules continued to grow I decided to build a larger wood cabinet out. I settled on three 24U wide cabinets using Stooge flat rails. I wanted the lowest cabinet to sit above the keyboard and slant upwards and the highest cabinet to slant downwards. After trying different designs I settled on three rectangular cabinets mounted on pivots so I could angle them however I wished. After I filled up these cabinets I used my original cabinet as a side-wing.
This photo shows pivot system that allows the cabinet to be rotated. In retrospect, I should have mounted the pivots towards the front as loaded cabinets are very front-heavy. Rubber washers between the cabinet and the side towers provide sufficient friction.
This photo shows the machined hardware. The power supply mounts to the two spacers to allow all-around cooling. The pivot mounts were made by welding 5/16" nuts to 2" fender washers that are screwed into T nuts on the inside of the cabinet.
Having run out of space again I decided to build a fourth cabinet. I decided to eliminate my side posts and pivots and simply stack the cabinets. I made a 6" high garage for the base to raise the lowest cabinet above the keyboard. In these pictures you can see the construction details including the power supply mounted on rails for all-around cooling, two MOTM-990 distribution boards, the rear of my mains power panel, and the enclosed back. Foam strips down the two sides block the slight gap between the end modules and the cabinet sides. The red connectors on the two MOTM-990 distribution boards are 2 pin connectors inserted on the +5 and ground pins of the 6 pin power pins. That way I can use them with four 4 pin power cables without fear of plugging them on wrong.
The finished cabinets are stacked four high with a full size piece of felt insert between cabinets. I used the pivots to anchor the cabinets together with large black fluted knobs and an aluminum strip. This is a very sturdy setup.
Even though the aluminum side rails hold the cabinets together, the felt sheets between cabinets is very slippery so there is some cabinet movement. It is especially noticeable with the side cabinets as there is a greater distance between the knobs. I decided to drill the top of each cabinet and insert cabinet pins to mate with a hole in the bottom of the next cabinet. These work great and really make the entire synthesizer stable. I machined one of the pins to a point which I insert in the top. When I put the next cabinet on top, it marks the center location of the hole to drill. Then I replace that with a pin and move the point to the other hole. Voila - perfectly matched holes.
Having run out of space again I used my rack as a side cabinet. When I ran out of room in that, I built a set of matching side cabinets. I dedicated one row to Dotcom format spacing.