Orrery

I want to build an orrery.
You might not know that word, but I’ll bet you’ve seen one. It’s a mechanical model of the solar system with planets turning around the sun. It was named after the Earl of Orrery who commisioned a watchmaker to construct a model of Newton’s planetary motions in 1700.

Orrery designed by James Ferguson. Adler Planeterium, Chicago.
Nowadays it’s easy to find digital ones (Science U, Orrery with NASA images, and Schools Observatory). Most of the beautiful mechanical ones are in museums but there are some contemporary orrery makers (John Gleave and Brian Grieg) and plans available for build-it-yourself orreries made of Legos and others from meccano/erector sets.
Of course I want to make one that isn’t of our solar system, but a system of my own invention. And in fact, my ultimate goal is to make one with complex motion–some of the planets have eliptical orbits and they won’t all be in the same plane. I know how it will look and how it moves. Now I have to figure out how to do it.
I wish Dad were still here. He’d be good at this.