This thing demonstrates a counterintuitive phenomenon while the center of geometry shape and the center of mass are not at the same position.

Homemade 3d printer

No

No

0.2

100%

This thing has flat bottom to lay on bed, no rafts or supports needed.

The STL file was created in AUTODESK INVENTOR, please scale it down to 1/10 to print.

Create an ellipse and revolve it into an egg shape object.

Cut this object with a slope

Create a shell for this egg.

Add a flat bottom for easy print

This simple design is focus on the concept of mass center and geometry center. In school, students are taught to use simplified math model to solve math or physics problems. But in real world, things are complicated which requires students think more on the details. I hope this thing help students have a better understanding on the concept it demonstrates.

This is a very simple design, students from middle school to high school are able to make it with basic inventor experience.

A working 3d printer and a computer with CAD softwares, such as INVENTOR.

This thing is all about the concept of the center of a thing. It can be a egg, a ball, a cube or even a shape nobody can name it. The step-by-step tutorial I posted in the previous section.

All the steps took me 10 minutes to draw and I believe students with basic CAD skill can draw this thing quickly.