pvc icosahedron joint

thingiverse

You can create a dome or a complete icosahedron with these joints and PVC lengths. Scaling up by 3% will give you some extra room for inserting the 3/8th PVC pipe. I used ABS plastic, which worked reasonably well, but the layers separated under stress. Maybe nylon would work better in this situation. No support material is needed to print this model (with ABS), although a heated platform is still recommended.