While technically it is already my second Z1 project, it started as my first PCB project that grew into a proper big project, so I hope this still works for the competition :) It is designed in a way that a well stocked Hack-/Makerspace could possibly built it with commonly available materials right away.

This build is mostly split in 2 parts: The PCB and the enclosure. I would suggest to only start with the enclosure once the PCB is done, as the PCB has the most opportunities for failure. The KiCad/ESP-home project is located here: https://github.com/9a/single_sided_7_segment_clock. One could also just use the enclosure and come up with a own design using standard larger size 7 segment modules.

BOM Electronics (recommendations, others will likely work also):

1x USB-C Wemos D1 mini (or compatible) with ESP8266
2x SN74HC595DR Shift register
29x 150080RS75000 bright red leds
8x 10 Ohm resistor 0805 (or 0603)
5x short 1/10th" jumper wires and pin-headers (or solder wires directly)

Hand soldering this was quite a challenge especially as I do not have the solder mask tools. Please post a remix if you have the means, the KiCad files are at https://github.com/9a/single_sided_7_segment_clock

Stock material:

3mm anodized aluminium sheet, at least two 150x60mm sheets
3mm colored acrylic sheet at least 50x100, best dark red
about 200x300mm sheet of ~3mm thick synthetic felt (or other flexible thick material)
100×80mm single sided copper clad PCB material
10x M3x6 Screws
some PETG/PLA

alternatively with 1/8" material one would needs to adapt the CAM files for the increased thickness, otherwise it will not be a problem.

See the esp_clock_combined* STEP files for the general assembly.

Please check the Makera CAM files before milling and always create the NC files yourself.

Steps:

Mill the PCB on single sided PCB material
Deburr the PCB using the soft, fine sandpaper of the Makera sanding block
Populate and test the PCB with a ESP, see https://github.com/9a/single_sided_7_segment_clock for details
3D print the 3dp_* STEP parts
Mill all the cnc_* STEP parts. If you want to generate the CAM files yourself: chamfers are 1.2mm on the outer big outlines and the USB port, 0.5mm on the other contours.
1. Setup 2 (front panel) is a two sided operation, the 5×5mm center mill during TOP should be used for center-probing when milling BOT.
2. Use double sided tape to hold the part during the BOT operation as the inner aluminium part otherwise could get loose.
Print the clock_mantle_template on paper and cut felt or any other thicker material. Add some margin to trim later
The M3 screws are meant to be self-tapping into the printed parts, mount the front and back plate to the main body for fitment of the felt mantle
To mount the felt mantle you can add double sided tape on the main body and lace it via the provided holes on the bottom. Trim felt to fit.
Use the outline of the milled sight glass to cut out a diffusor, normal paper works fine but “LED diffusor foil” also works
Sandwich the segment mask, diffusor, sight glass and front plate using 2 M3 screws, see Youtube video above
The ESP sits inside the backplate with the USB-C slightly protruding into the back aluminium panel
Add the feet, the M3 screws should be self tapping.

Please comment if anything is creating problems, this is quite an involved project and I tried my best, but it was iteratively created and may have some inconsistent data.