You're 1800's commentary was appropriate. The relays clicking and incandescent bulbs flashing took me back to my 1800's which was the cusp of the 80's when I was in tech school.
Honest Ed's Emporium in Toronto, Ontario was the place for apartment-dwelling college students to outfit rooms on a budget. It was a dollar store before dollar stores starting selling stuff for $1.25. The store signage was big and flashy, using 60watt bulbs, much like a Carnaval marque. As I stood and watched the lights flash I could hear a click as the lights went on and off.
Sneaking a peek around back of the sign, the lights were switched with a rotor from a distributor. It was so cool to watch this rotor spinning around and lights going on and off. I don't know who built it or if it was up to a code but it worked. It was switching a few hundred lights around the edge of the sign so I suspect there was some current.
Your relay clicks and flashing lights took me back to a time much in the past. Cool project. What did it cost for the PCB sign board? I'm curious because of its size.