In 1750 James Ferguson, a self-educated Scottish astronomer, built what he called a "mechanical paradox". This is an attempt to replicate his design. An article on the design and it's original maker (pun intended) can be found here. I used the description of Ferguson's design and the illustrations from his original text. I did not use the design from 'Digital Machinist' (I could not obtain a copy of that). There are some other plans available on the Internet to duplicate Ferguson's model. I did not use those either, but I did view pictures of completed versions of those. Google "Mechanical Paradox Orrery" if you want to find more information and images. BTW, Ferguson's written description included a single gear in the center to drive the three gears at the end, but his later orrery design showed three stacked gears in the center. I used a single gear in this model, I will post the files for the three central gear "stack" later. I have not yet printed the parts for this, so I don't entirely know whether it will work. My 3D printer is ailing but parts are ordered, so I hope to get back to making stuff soon. Ferguson also turned his "paradox" design into an "orrery" also correctly called a "tellurion". I hope to do that soon too. Stay tuned.