With the help of a company we are working with, we made tremendous progress in the choice of our mechanical architecture. Here is what we settled with:
Each “floor” of the structure is being held to its neighbours by three spacers in an equilateral triangle. The spacers and plates are made of metal (most likely aluminium) and carry the ground from the body (it is being pulled from the arm).
The 12V power is carried through the motor axis which is isolated from the bottom plate.
LED band PCBs are simply held by friction and by their connector. Appropriate holes in the hat and the middle plate are made to fit the PCBs properly and hold them in place. Since they are very small and light, this should be enough. The remaining unknown is if they are going to resist the centrifugal force.
We made a document with the dimensions of LitSpin. The PCBs are at scale, and after printing it we could get a better grasp on the actual size of the system. The LED bands are so tiny !
One major issue we have with this design is the hat. We would like to make it transparent in the future, but it is still unsure whether or not this will be feasible. We would need a transparent material that can survive the rotation, be perfectly flat and be light. This is no easy problem.