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: 

- wooden plate / base 

- one stepper 28BYJ-48 

- one bearing (external diameter 26mm, hight 8mm) 

- metal bars (6mm - to connect central gear with hour 'box' holders, 3mm - to connect hour 'box' with 'box' holder)

REMARKS: 

- make a hole / pocket in wooden base, where track with rotating part will be placed 

- be very precise finding spot to mount central gear! Every mm of difference can block whole mechanism  

- connect track parts precise, to let mechanism move easily. In case of problems, you can smooth out imperfections with sandpaper 

- distance between centre of central gear and center of stepper gear is 55mm. 

- stepper should be mounted quite deep into wooden base, to not block rotation of mechanism. 

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).