Greg Zumnwalt's Second-Generation Pick-and-Place Marblevator Is Hypnotic to Watch

Maker and 3D printing enthusiast Greg Zumnwalt has put together a second-generation "Marblevator" marble run based on a pick-and-place system — and featuring a crank-turning smiling robot for good measure.

"'Marblevator, Pick and Place, Version 2' is my second 'pick and place mechanism' based Marblevator," Zumnwalt writes of his latest fully 3D-printed build. "In this model, I've replaced the magnetic marble gripper used in my previous pick and place model with a hybrid PLA/TPU gripper which, so far, has operated over 72 hours with a marble drop!"

The entire marble run is designed in Autodesk Fusion 360 and printed in PLA on an Ultimaker S5s 3D printer, bar a few necessary off-the-shelf components: TPU rubber pads, a single DC motor, two AA batteries for power, a switched battery pack, and a few wires — plus, of course, the metal marble that the crank-turning robot keeps whizzing around the track.

"This is a high precision print and assembly model using at times very small parts and in very tight spaces," Zumnwalt warns. "Prior to assembly, test fit and trim, file, sand, etc. all parts as necessary for smooth movement of moving surfaces and tight fit for non-moving surfaces."

"Depending on your printer, your printer settings, and the colors you chose," Zumnwalt continues, "more or less trimming, filing, and/or sanding may be required. Carefully file all edges that contacted the build plate to make absolutely certain that all build plate 'ooze' is removed and that all edges are smooth. I used small jewelers files and plenty of patience to perform this step."

A video of the Marblevator in action is available on Zumnwalt's YouTube channel, while anyone eager to build their own can find the STL files and instructions on Instructables.