How much does it cost? The guest passes for hacker conferences are full-on computers these days, if this is in the same price bracket it would be a great idea for those.
Just as a point of interest perhaps for folks who are not familiar with PCB design and modern electronics: the "huge" matrix of 21x21=441 LEDs would, with the specified LED from the bill of materials (BOM) cost all of $6.
That is based on the price for low quantity (1-500 pieces) though; if you were to build more than one board you would buy more LEDs, pushing the per-LED price (way) down. You can get 4,000 LEDs for $30.'
Edit: here is the LED in question, from the BOM [1].
I don't know, I struggle with a light switch, but that doesn't look like board someone took home with a box of parts and a soldering iron to make at home.
Are there services that you can send the BOM and board files too, and not only do you get the PC board back, but it's populated? Will they do that for a onesy-twosy thing like this?
Then all you have to do is supply the battery and download the firmware (however that is done).
Not if you're at a trade show in an industry where a single deal can net millions of dollars, and a small booth might cost $15k just for the space for a few days.
There's definitely an entire business available for expensive trade show merchandise, including electronic business cards. People routinely give away shirts and other merchandise that cost far more than $10..
Now whether you get it populated or not..
https://github.com/Nicholas-L-Johnson/flip-card/blob/main/ki...