The 7 rows of tubing are held together with a threaded (6-32) rod poked through holes that were drilled in the fittings at each corner. I used a brass nut at the bottom of each rod and a brass knurled knob at the top. I continued by making the "lid" that covers the base. The lid is made by pop-riveting the copper tubes to pieces of aluminum angle stock from underneath. There's enough room inside the base for 4 hard drives, a water pump, and a water reservoir...in case I decide to watercool something.
I left a big hole above the CDROM/PS for all of the cables. Another hole was required for mounting the (later discarded) monitor arm. Just like the base, I stacked hoops of copper tube and made the lower part of the motherboard 'cage'.
Starting to look like something now