This is a mod of Jeremy Blythe's raspberry Pi solenoid alarm bell. I turned it into a kind of Christmas decoration/art thingy, prototyping on an arduino and then moved it to an Attiny45 for implementation. The sign is just an acrylic photo holder with a printed message. US visitors will recognize the reference to the inescapable seasonal movie, "It's a Wonderful Life".
The sketch is trivial. It's just the arduino Blink example with a HIGH for 80ms, then LOW. The low has a random delay of 30 seconds to 2 minutes.