I designed this topper for an 16 string 180 degree mega tree. I used sainsmart TPU with solid infill and it works great. I made it so that a 1/4 inch threaded rod( along with 2 washers and 2 lock nuts) could be inserted through the hole in the back for stability and to squeeze the 3/4 inch EMT pipe. I also added holes for 2 zip ties to be used around EMT pipe and vertical supports.

Update 8/24/23: I now have a 20 string version with a diameter of 10in/ 254mm