I recall reading that a magazine called "Digital Machinist" (I think that's the title, I may be wrong) did an article on one's construction. Never seen it. Supposedly it was based on the Ferguson type Orreries which I am particularly interested in.
Ferguson's book: Select Mechanical Exercises is on my list of books to get. Since it was published in the late 1700s, one would assume it to be online somewhere in pdf but it isn't.