Sorry for the delayed response, I have a lot of irons in the fire. If you prefer to go with the solid aluminum frame, 10mm will be more than enough. It sounds like you don't have ready access to a welder, do you have access to a drill press? or at least a good drill, steady hands, a bullet level, duct tape, a willing friend? You can drill and tap holes in the ends of the cross members, say about m5 size, and then drill cross holes in the longitudinal members to line up with them, then the vertical members. The problem with this method is maintaining alignment, you could very easily waste a lot of materials. You should ask around a few shops, you would be surprised how many of them "know someone" that has a mig/tig at home a knows how to weld aluminum. As for touchscreen displays, you already got the advice that will serve you best, there have been a number of open source projects working on this, and the liliputs are pretty standard. Now your cooling setup, why push pull? The diff between that and just push alone is ~1d, not worth the effort, added cost, or wasted space in my opinion. When considering running dual vs single loop, IIRC the basic consideration is pressure vs. restriction. When you intend to cool everything plus multiple GPU's then you should really run dual loop because the restriction/backpressure will be so high that the last devices on the loop will see almost no cooling benefit. If you go dual loop then it you need 1 res for each loop, other wise it will still be a single loop with bad pressure on one branch. If you decide to run single loop then dual ddc in series will be a necessity. They will give the best pressure. This is inherently safer because if one pump dies the other should keep things cool enough to prevent a complete meltdown. Trade-offs for either method, although dual will cost more, it should also provide more consistent cooling.