The Napkin Ring Problem

Recall the "napkin ring problem": Take a sphere of radius _r_ and drill a hole along a diameter so the resulting shape has height _h_. Then the volume, _V_ = π_h³_/6, does not depend on _r_!

These files consist of drilled spheres of the type described in the problem. Each has a height of 4cm, but the radii are 4.15 cm, 5 cm, 7 cm, and 10 cm. **It is essential that you print them with 100% fill**. If you do, you will find that they all weigh the same amount and hence have the same volume.

Thank you to Colm Mulcahy for suggesting this project.