Just a Little Funny One.
Well, well, well, this one's just way, way, way too easy...
Here's how it works. When the marble descends the sloped track from left to right, it is over rotated by the design of the track which gives it just enough momentum to climb the vertical section.
Perpetual motion.
:)
Designed using Autodesk Fusion 360, sliced using Ultimaker Cura 4.12.1, and 3D printed in PLA on Ultimaker S5s.