This model was created to enable modeling of structural shapes with flexible joints.    I have printed in PETG, but wasn't sufficiently flexible.  I haven't tried TPU.  I would love to know what others on printables think about making it better.

My background is civil/structural engineering.  Years ago I had materials available for modeling chemical compounds, and these worked well for demonstrating structural systems which would work with fully flexible joints.  I used these to demonstrate that a triangular shape is the basic building block for trusses in a plane.  I then extrapolated to show that a 3D shape with triangular faces (a tetrahedron) is the equivalent building block for space trusses.