So I was trying to figure out a way to have 12 different meeples for Dixit, and I bought a bag of colored glass marbles, the idea for the meeples wasn't good, so I scrapped it but I still had a bunch of marbles sitting unused, so I remembered the Astrolabicon by @MakeAnything, looked for it but I couldn't be sure his design would work with my marbles, so I decided to start from scratch and design something I could be sure worked. 

A while ago I bought some 8*2mm round magnets that really are 1.6mm thick, and the diameter of my marbles are not very precise, being between 14-14.8mm. I figured I might have to tweak his design anyway to fit my marbles and magnets, so I ventured and took the idea with a design all of my own.  

I started with an octagonal shape, a 15mm rail for the marbles to run through and I had to find the perfect size of the octagon in order for the two halves of the object to hold the same amount of marbles, as I didn't want to have too much slack between marbles. Also the proportion of marbles in each ring given a regular octagon shape, it ended being 8, 20, 20, 8. I found this information out by drawing a ring of 15mm circles of different quantities, and figuring the radius of the rail where they would go.

This shape allows for more complications as every rail can connect to 3 different rail loops.

The overall shape is almost spherical as well, so the octolabicon looks more like a ball than a complex geometric shape, although when twisted, the rail shapes look very cool.