Hooke joint and CV joint
A basic universal joint (Hooke joint) allows a rotating shaft to flex, but the output speed is not constant. This can cause vibration and premature failure.
Adding a second Hooke joint can cancel out the effect, creating a Constant Velocity joint. James modelled these joints with BricsCAD Platinum. Again, we had a small lisp program to rotate the shaft, flex the armature and render the model at each position.