#radix looks great but it looks like they only do round and square
https://printing.radix.coop/product/round-stickers
https://www.reddit.com/r/opensource/comments/binxe6/question_does_someone_have_any_idea_about_how/
I finally went with https://diginate.com for the @mobian stickers, and also ordered some samples from Sticker Mule. I received both today, and prefer the Diginate ones (on the right):
* more contrast, colors are more vivid
* powerful editor to precisely adjust the cutting mask and padding (avoid unwanted white borders)
* accept 600dpi pictures for a slightly more detailed result
Both look nice and are well cut though, and the photo really doesn't do them justice
Have I already mentioned that my subject Macroeconometrics has a HEX sticker now? ...and it can be reproduced in R: https://github.com/donotdespair/naklejki/tree/master/mcxs