Summary

Sphere with additional radial deformation of SphericalHarmonics.
out.stl: l=15,m=2

Instructions

more to come, I am writing on a c++ program to create those shapes..
You can download the program for windows here: https://github.com/bkubicek/sphericalator/downloads
Otherwise compile yourself using qt>4.7

Spherical Harmonics are also the solution for SchrÃ¶dinger's Equation in the non-radial part. So you can geek out and imagine its either nuclear cores that are vibrating, or a strange "visualization" of exited hydrogen atom.

see e.g. http://en.wikipedia.org/wiki/Spherical_harmonics
or http://mathworld.wolfram.com/SphericalHarmonic.html

I have not printed any yet, probably support would be required.

Spherical Harmonic Christmas Sphere