Double Cone & Ramp
This classic demo appears to defy the laws of Physics by making double cone rolling "up hill". The combination of the shape of the cones the "V" shaped ramp make it look like cone is going up, but after further inspection you will notice the center of mass of the cone actual goes down.
The double cone is made of 2 cones superglued together. The cones and the ramp can be printed at the same time. Print time at medium speed was about 3 hrs.
Since the part is printed in layers, the surface that the cone rolls on will be stepped. I sanded the surface on a belt sander to smooth it before using.