Bob Blick have built this propeller clock some time ago, but it still serves as an example for other modifications.
A motor spins the “propeller”, and a PIC16F84 microcontroller keeps track of time and changes the pattern on seven LEDs with exact timing to simulate a 7 by 30 array of LEDs. Moving led array makes illusion of flat image. Author provided all necessary material including circuit, PCB, and source code that may help to build it for everyone.
i liked it………….