More DIY pace clock ideas for USRPT sets

I was thinking about using my DIY pace clock for USRPT sets this evening and an enhancement occurred to me. It should be possible to add a set of LEDs or something similar to the face of the clock that light up at the “set off” times. Not sure how many swimmers I might have in a lane at a time, but perhaps it would even be possible to have different colour LEDs for different swimmers and to have them flash for a few seconds before lighting up. After the target time the LEDs would switch off, so the swimmers have to try to complete the distance before “their” LED goes out. I reckon that could all be done using an Arduino. I’d just need some method to set the target and turnaround time, but that should be possible with some switches. Oh, and a “start” button, too. Haven’t worked out how to make it work for two clocks at each end of the pool for 25m or 75m sets yet, but it surely can’t be that difficult.