Interesting clock design. Rotating hour indicates minutes.
There are three hour boxes with numbers. Indicator on moving hour 'box' indicates minutes past visible hour.
With every rotation boxes are turned to indicate next hour. Turning takes place in one, special track piece.
Full rotation takes 3 hours and 5 full step motor rotations (central gear to stepper gear ratio is 1:5), so to proper show time stepper has to make 10240 steps per three hours.
Steering of stepper can be made by Arduino or other device controlling stepper motors.
Besides 3d printed parts, you'll need:
REMARKS:
Photos and video (https://www.icloud.com/sharedalbum/pl-pl/#B0uGeA5r4GIpQg9;90D8E00E-4B61-47E6-9BCC-7C2FB7D0815D) of prototype! :)
3D PRINTING SETTINGS
Downloading you will get separate stls files for every single part of clock. Please note, that you need three 'box' holders and six track pieces (including one with rotating mechanism).
Printing remaining five track parts you can choose full track or cut track file (to shorten the printing time).