Last time I did a mosaic demo it was a Christmas market event at an art gallery in Georgetown, Texas, in 2019, and I brought a piece featuring a manatee that I had just started working on. I picked away at it for a couple of hours, politely answering questions from the occasional bored adult who wandered through--until an entire Girl Scout troop stopped by. They were probably nine or ten; that cool, interesting late elementary school age. Their troop's float had won first place in the town Christmas parade that morning, so they were super effusive and high on their success.
They unselfconsciously hijacked my project, gluing in tiles any which way and advising me that I should really incorporate a tsunami into the design. It was an absolute blast. (Though I admit I did scrape most of their work off the board after I was sure they were gone.)
I'll probably never quite recreate the magic from that encounter, but I'm keeping the fun of that afternoon in mind as I prepare my piece for Saturday. The idea is I'll have a primary image already in place, and anyone who stops by will be welcome to add something to the background. I'm in an interesting spot, design-wise, as I'd like to have something elaborate and pretty enough to give people an idea of the possibilities of the art form, but also something simple enough that no one will feel weird about letting their six-year-old glue a bunch of shit to. I think I can straddle that.