Various companies offer various fancy permutations of stickers; vinyl, transparent, holographic, custom shapes…
Classic hack: upload your sticker designs to a print-on-demand site like Redbubble and people might even pay you for them.
A nerdy cult phenomenon. Nerdy hexagonal promo stickers that tesselate, for people who find it needful to promote things tesselated, and also honey bees. The specifications ensure that this remains standardised, and the full standard is excellent, including such clauses as section 2.
When you exchange stickers, you may be given a sticker that does not conform to this specification. If this is the case, thank them for the time spent on designing and printing the sticker.
Emi Tanaka explains and gives a powerpoint template that is useful for this purpose
The R package hexSticker automatically generates stickers to the required hex sticker specification from your graphics.
Pre-designed stickers are available on e.g. pilcrow’s redbubble shop. NB, the redbubble sticker specs (external 76mmx88mm) do not match the official hexbin specs (internal 43.9mmx50.8mm), so you might face standards incompatibility mixing them with other stickers from other sources.