https://youtu.be/TpHZNPlkLpY "Marblevator, Spirals" is a two revolution downward spiraling Marblevator incorporating what I refer to as an "inverse auger" design. In traditional "Archimedes Screw" styled marble lifts (I refer to the "screw" here as an "auger"), the auger is in the center and rotates while the guide rails are external and stationary. In this model, the guides are in the center and rotate while the auger is external and stationary and holds the spiraled track. Designing the model in this manner provides easier 3D printing without the need for supports. However, I also designed the track so that it would "over rotate" the marbles to slow their descent. The model uses 8mm ball bearings for marbles, and the track rails are 7.9mm wide, so the ball bearing rides down the track rails and not the track bottom, which over rotates the ball bearings thus providing a slower descent. So with dimensions this tight I used the "Engineering Profile" in Cura 4.1.0 for accurate 3D printed parts the model requires. Designed using Autodesk Fusion 360, sliced using Ultimaker Cura 4.1.0, and 3D printed in PLA on Ultimaker S5s.