Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:5162187.
Stratasys destroys more and more the thingiverse-infrastructure. So my project from March 2021 was not visible anymore and Stratasys didn't react on any of my meanwhile five issue requests regarding different bugs in the platform I had to publish this project again to make it visible to you.
I was excited by the design and solutions of hollow clocks. But all of them are running with only quartz accuracy and needs permanent correctures. So I used an ESP8266 NodeMCU to obtain the time from internet and added a correcture for rounding errors from time-values to steps to the software. Additionally the change from CET to CEST and back is considered automatically. So the clock nevermore has to be to corrected. Because the ESP8266 is a bit longer than the Arduino Nano I had to create the base completely new from scratch to fit the new PCB. Additionally I splitted the base to be able to print it without support. Two additional holes makes it easier to mount the motor with its screws and a cover hides this ugly stepper.
The firmware for the ESP8266 is available on github (it's still under construction there)
Edit 2021/03/28: Btw: CEST correction worked fine. When I woke up this morning the clock was showing the correct CEST-time. ;-)