Designing the supports for the round acrylic tube mounts was a challenge. My first thought was to use a ~2.5 X 12" piece of of acrylic and bend it four times, making it a square tube. This would have worked, but I have not built an acrylic bender yet. Instead I cut up and reused some 3" heavy cardboard tubes that were used in rolls of large format printer paper. This way I could use wood glue to attach plywood to the bottom and glue pieces of wood to the sides for holding screws. This worked well, and now I have 3 large supports and 2 small supports. The remaining two acrylic discs do not get supports, they will be mounted on a thin 1/4" disc of plywood, close to the wall.
I picked up 28 1-1/4" machine screws and began attaching my PEX tubes to the discs. They are only on there temporarily in the photo because I still need to take them off to paint the supports and paint over the lines on the wall. To attach the tubes to the wood, I cut a bunch of small 3/4" X 2" rectangles of acrylic and roughed up the front surface on the belt sander. When it was time to attach the PEX tubes, I already had one end screwed to the support, placed my acrylic rectangle, and marked spots to drill the holes. After drilling and screwing with some 1/2" sheet metal screws, I used a dremel cutoff wheel to score some lines in the back side of the PEX tubing so hot glue could grip it. This worked well because the hot glue cooled quickly, minimizing the time I had to stand on the ladder holding each tube in place. The next step is to build one more support for the bottom third of the sculpture. When this is in place, I will take the tubes off and paint the wall and supports.