Simple enough.
¾" Schedule 40 PVC. You can use 1". It is stronger, but you really don't need it, I hang lots more on mine and I used ¾".
Build a box 3' X 4' (although 3' is wider than you need, 2' is wide enough) and 40" high. The box keeps it from falling over.
In the center of each end, add vertical columns 3' high (This brings the overall height to about 6' 4"). Connect them with a 4' section of pipe.
You can either hang hangers on the rack, build in hangers or use a combination.
If you're going to use hangers, you're done. If you want to build them in, drop them where ever they work best for you. Use a 6" drop with 16" shoulders. That'll work for BC, wet suit and skin. For gloves and boots, frop another hanger with 4 vertical posts. I'd put the BC hanger on the top rail of the box and the hangers for the wet suit & skin on the very top.
Hanging regs is not a good idea, I'd put them on a shelf. I hang my mask on the shoiulder of my BC and I added another hanger for my fins.