Roly Poly Toy, Self-Righting Model

####Roly-Poly Toy, Self-Righting Doll: Simply Playful!

I got a little challenge: design and print a self-righting model such as a roly-poly toy. One way or the other, we have to play with the “center of mass.” There seem to be two ways to do it: (1) Manipulate the infill rate during slicing to change the center of mass; and some slicers do support that. I tried variable infill (Flash Print 5) with the light bulb model and it works well. I used a 70-90% infill rate for the top half of the sphere, leaving the rest to be 5% infill or less. (2) Design the model to be partially hollow and use a high infill rate (50% or higher) during slicing. **They are quite playful. Try to push them or spin them and see what happens**.

Among the files are two models. One maintains a vertical position at rest; the other tilts at an angle of about 50 degrees because of the design.

####References

1. https://en.wikipedia.org/wiki/Roly-poly_toy
2. http://hyperphysics.phy-astr.gsu.edu