Hình dạng Rattleback (Celtic stone)

A rattleback, or Celtic stone, is an asymmetrical, semi-ellipsoidal object that exhibits a peculiar motion where it spins stably in one direction but wobbles and reverses when spun in the opposite direction due to its uneven mass distribution and curvature.

Print info:
Print with 100% infill and make sure to smooth the survace of the Print using sand paper for the best effect.