Split flap displays were widely used in railway stations, airports etc. I loved watching the boards of the rolling characters. They have mostly been replaced with electronic devices nowadays, The module here is based on a popular cheap stepper motor, 28BYJ-48, driven by arduino. The design represents a single position of a character. It can store 32 characters in it (this is the number of flaps). The motor is hidden inside the body cylinder, so the duplicated devices can be easily placed in a row to make the entire words. No pulleys, no timing belts.

Note 1. The design does not contain any handle. Use two M4 screws to mount it to your preferred base or drill whatever holes you need in the motor holder piece. I used a thick wire to make the temporary stand.

Note 2. The thick wire is also used to set the flipping point of the top flap in this prototype. It was the easiest way to tune the correct position; however, it's just a stopgap solution. For the final design it could be printed extension of the handle or just the front panel.

Note 3. There is no position sensor. The driver keeps counting the steps to identify the currently displayed character. It is not reliable method though. The motor does not make the perfect angle per step, probably due to the gearing. It can be dealt with by adjusting the driver code, but in the long run this particular split-flap is better suited to work as a dice than a display :-)

Enjoy the flipping!