If you look closely, you'll see these in weekend events I've attended since late 2017 -- because I've been providing them. If you would like to make your own for your scene or event, simply print the Lead and Follow PDFs (or download the images here) on a sheet of thirty 1x2-5/8-inch colored address labels. For ease in transportation, I then cut the sheets in half (15 stickers per half-sheet). To download the template images, click on the "Select Photos" button at the top right of the screen, then click on the thumbnails to select, and finally click on "Download" back in the upper right corner.
I used the following products, which (factoring in ink) work out to about 20 cents per sheet of 30 stickers, but any Avery 5160-compatible labels will match the provided images:
https://www.amazon.com/gp/product/B01M4S0H6N
https://www.amazon.com/gp/product/B01M2DA9JR
(Proudly made in the USA!)