4159 worked on a similar system involving tube connectors (Aluminum not 3d printed) over the summer and the start of this year. We had to abandon the project due to time constraints but I really think a lot of the work we did could be converted to your system using 3D printed parts.
This was one of my favorite parts that we worked on.
It will allow 2 tubes to freely pivot between an angle you could set. It uses a shoulder bolt and some CNC milled parts that could be replaced with 3d printed stuff. One interesting application would be the intakes like the madtown design from this year.
Other stuff we worked on/had ideas about:
2 way/3 way fixed connectors
2 way fixed connectors that you could adjust the angle of
More stuff I’m forgetting
I would love to help you guys continue this project and build it into something even larger. I’ve always thought that more could be done in the area of low cost, rapid prototyping. If you want any CAD files or an explanation of things I’ve mentioned please lmk.