It took me longer than anticipated — a couple of events in the middle of it got in the way — but the Rainbow Jellyfish kits are now in stock on Tindie. You can get them here: https://www.tindie.com/products/13347/

Here's a shot of completing the first ten kits:

The LEDs are dabbed in paint to show what color they are. I used SD card boxes for the kits — was considering paper bags with printed instructions instead, but this turned out to be easier and required less work. Also looks better.