Jason designed a persistence of vision hard drive clock. He etched numbers on a copper disk and added 8 LEDs below it. Each LED represents a character on the display and blinks when the corresponding digit passes over it. His project is Arduino-based, and the project files can be downloaded from GitHub.
My replacement platter was cut out of FR4 single sided copper clad board using a 70mm holesaw. A smaller holesaw (19mm I think) was used to cut out the centre, which was then filed to snugly fit the hub of the 2.5″ laptop drive. The digits were actually laid out in EAGLE (PCB designer) since it was the only package I had to hand which let you type in rotation angles for characters. This worked OK, but a decent vector drawing package will have more interesting font options. The platter was etched just like a PCB.