I really should come back here more often and check for replies.
To answer your question, this machine comes after building around 15 wooden geared orreries, and I guess that building them was really a training program of sorts to give me the skills to tackle this beasty - something that I've wanted to do for the past decade or so. There's no way I could have done this even two or three years ago, I just didn't have the experience back then.
As for the design, well the basic gear trains you can find all over the Internet - it is, at the end of the day, just gears driving gears (with a couple of unusual bits thrown in just to spice things up a bit). So if you can read a basic gear diagram then you are half way there - all the raw information is out there. All you have to do then is cut them out, mount them into a framework of some description, and hey pesto,
one antikythera mechanism! In truth, I guess that there was a good year or so of research before I got anywhere near cutting a component, and even now I'm learning about the mechanism and changing bits as I go along. Some things aren't obvious until you actually try and build one.
If you want to learn more about the original and the research that's gone into it, the Wikipedia article on the machine is now very, very good, have a peak if you get a chance.
in the mean time, here are two films of the latest test fits of two halves of the main gear train before full assembly.
Anrikythera mechanism main gear train part 2.: https://youtu.be/5u4eW5zXXlU
Antikythera mechanism wooden replica: https://youtu.be/2dE5drxJv9I