Spherical 3 pipe coupling for 16 and 8 mm pipes

I've created this coupling to be able to construct things with pipes (16 mm).
I've seen similar couplers used in scaffolding.
You will need a M4 40 mm screw with nut for each coupler, preferably insex or torx.

I've used 16 mm installation pipe for electrical wiring PVC. Any 16 mm pipe will do, choose a pipe that will give you enough rigidity.

If you find my design useful please give me a TIP