Reviving this old thread to say thank you for the info - it gave me the ideas needed to build my own, high quality light rack.
I just ordered a bunch of 80/20 product from Ebay to build my own rack for four Mitras. Cost was significant, nearly $400 shipped, although I opted for a lot of extras including rubber feet, wire management channels, etc. The Reefbreeders racks sold by
http://reefkoi.com are quite reasonably priced... I am doing a different configuration, mounting the lights with the long side perpendicular to the front of the tank, which required extra extrusions and brackets that added to the cost. I am thinking the assembly time will be quite low, probably an hour or two at most.
The Mitras have female M4 x 0.7 threads in the chassis and the wire suspensions have female M6 x 1.0 threads. The wiring suspensions can be attached to the 80/20 T-slot by the connecting screw/cap set showing the earlier photos in this thread, which I found at Home Depot but not Lowe's; M6 T-studs (80/20 part#13444, not listed on Ebay but they will add to your order); or T-nuts with M6 threads and M6 x 25mm set screws. I opted for the ball-spring loaded, self-aligning M6 T-nuts and set screws, latter sourced from Home Depot.
I opted for the black anodized aluminum since it will match the black Mitras. Once the parts arrive and I assemble I will start a new thread with photos and links to the actual parts ordered.