Through popular request by Reddit, this is the clock I built and designed from scratch. The original plan was to use a stepper motor and have it controlled by Alexa, (So you could say, "Hey Alexa, change the time to GMT" or so on), but I ran out of time and don't think I'll be finishing any time soon as I have other more important things to work on!

I have to find my Arduino source code for the stepper motor drive, but it's not rocket science if you want to work on it. (Your center wheel is the key here. Your drive gear is exactly half the teeth of the seconds hand. So set your stepper motor to spin twice in 1 minute, you have seconds. While programming in time setting will need some work.)

I have printed the clock, it works just fine. However, here are a few notes/fixes that I think would be good to do.

1. The supports for the middle gears like to come out, as they are not fastened down. I would make a cap with a screw in both towers.

2. Size issues. I made all surfaces that spin a little tighter than I should've. It helps to take a bit of sandpaper to the gear holes to make it spin freely. (Or make the holes bigger on the STL!

3. In order to keep the gears on, I bought external retaining rings to hold them on. (Part 97633A170 from Mcmaster Carr.)

4. Biggest problem with the project- I was originally going to have a servo pick up the small carrier gear (between drive and seconds) and lift it to minutes in order to save time when changing timezones. This did not work. I would pursue a better idea, or if you want steady drive just make that middle gear a travel gear and lock it in place. (This goes for lifter arm, lifter, and small dowel as well.)

5. The 2 piece gear should be press together with mild sanding. Glue also works well.

6. Please note that the final clock movement is for assembly help only, do not try and print that. It will end poorly. It also has the Mk1 motor mount. Which was wrong for my stepper motor. That will most likely have to be redesigned for your stepper motor anyway, but I did include my version as well. Arduino is standard size with a standard stepper motor controller.

Like I said, I just ran out of time. I hope someone can take a look at it and make something of it. If you have any questions feel free to ask here.