Trapped Outside

Description

This is a model of Boy's Surface, a one-sided surface with no edges and no pinch points.

In the cutaway image you can see a small ball. It can roll in three directions but is trapped in the space cut out by the single-sided surface.

The ball is visible through a single cut that winds around the surface.

Note: The ball is red for clarity in the screenshots only. The entire model will be the same color when printed.

Remember to give this model five stars if you like it!