DIY bicycle chain clock - upcycled!

Idea taken from here:

https://makezine.com/2015/06/05/upcycled-bike-chain-becomes-funky-timepiece/

adapted for 3D printing.

I built the clock around a 0.9° NEMA 17 Stepper Motor.
I used an esp8266 I had laying around to drive the motor with an A4988 stepper motor driver.
It makes one step every 36 seconds and has a little switch to speed it up for setting the clock.
All is powered with a 12V power supply at 0.25A; the esp8266 is connected to power through a small buck converter.
Since the components for warm at about 40°C, I added a small 30mm fan to it.

The Shimano Cassette goes on a holder with appropriate spline and it's secured with a cover from the front with an M6 screw.
All this is put on the shaft of the motor and good with an M3 screw from the side.

You can see the clock running in fast forward over here:

https://youtu.be/3Xcgl1KENr4

The numbers are secured to the chain with a drop of super glue.

Chain has 8 links between the numbers and sprocket u