What's OnStep Today?
OnStep is an open source automated motion control system designed to operate the mountings under telescopes and other astronomical instruments. Its emphasis is on astronomy and astrophotography.
Also second not insignificant aspect of OnStep is cost. On commercial automated telescope mounts the electronic control systems add 50 to 70% to the price of an unautomated system. In my experience, too many of these systems have proven to be short lived and unreliable, repair parts are often unavailable or horribly overpriced. Repair when available, is equably expensive, often less than competent and requires shipping heavy equipment thousand of miles or for folks in other markets across oceans. Other mounts, names like, Byers, Takahashi, Astro Physics, Losmandy, etc. can retain their mechanical soundness well beyond that of their limited control systems and are due for an update. And of course nothing sadder than a expensive mount that is now a doorstop due a failed system.
There is nothing magic about the design of the systems. Anyone with basic hand skills can work with them. The magic is in the operating software. Developed as freeware by Howard Dutton and constantly improved by members of the Google OnStep group over the last decade it has been adopted as a commercial product by unrelated enmities in Asia. Yet it remains mainly a user directed and designed project. Do-it yourself is generally the least expensive path to converting or adapting OnStep to your project. An I encourage those interested in OnStep to take that approach.
I see my part as administering a group buy to save on the cost of parts for building the controllers. However, being too wise or lazy to administer group buys, I front the money to inventory the parts for commonly built controllers and recover the costs when kits are shipped. I use Paypal, they keep the books and assume performance on my part.
The economies of buying part in units of up to 1,000 is considerable. Much of the cost of individuals trying to source enough parts for one controller is in the shipping expense. Pretty much everything for a controller is manufacture or assembled in Asia and shipped by air. This usually entailed a lengthy wait for shipments. I usually have most of the parts on hand, so it's just a mater of how slow I am and at least you can complain to me personally about that.
The OnStep Wiki has much of the information you need to accomplish your project. Please note the "Pages" button at the bottom of each Wiki page. Using the button opens a drop down menu of informational and instructional pages.