Price was my secondary consideration, but it's still an important one. Why throw away money on an Arduino for no reason?There was no mention of cost that I saw, just they wanted ideas on how to do it.
And more to the point, he'd have to study up and learn programming to use an Arduino. It's far more sensible to use a 555 or a 556. I'm prepared to draw the circuit, and he only has to solder it up.
As I said, an Arduino is overkill for this purpose.