Ball and cup toy.

thingiverse

The ball and cup toy features a 25mm ball seated loosely inside a 200mm tall cup, ensuring a captivating dropping mechanism. To assemble this intriguing design, it's essential to utilize support during construction, given that a 25mm diameter ball with a tiny 4mm hole resides within the cup. Notably, the ball doesn't come into contact with the cup's inner wall. Once support is removed or dissolved, the loose ball will inevitably fall. For added realism, attach the floating ball to the underside of the cup using an exceptionally thin string or shoelace, thereby creating an impressive visual effect that simulates the sensation of a rolling globe inside a towering glass container.