A prototype design for what I'm calling an "inverse auger" marble lifting mechanism.

In traditional "Archimedes Screw" styled marble lifts, the auger is in the center and the guide rails are external. I've created quite a few "Marblevators" using this technique, however, the auger can be difficult to 3D print in one piece even with supports.

In this design, the guide rails are in the center and the auger is external. Rotating the guide rail causes the marble to follow the external auger. Both pieces 3D print with ease and without support.

Video is here: https://youtu.be/QEpeEL6qLmA