Sticker Mule

Stickers are so much fun. Sticker Mule is the easiest way to buy custom stickers. Thousands of people, startups, bloggers, developers, and companies buy our amazing stickers printed with the greatest care and sent in the fastest way possible. Shipping costs are free as well as offering immediate customer support.
Promote your business or show off your support for your favorite open source project, non-profit cause, or startup with stickers. Sticker Mule is positioned as the favorite place to print your stickers across the network.

Find more about stickermule support for WordCamps: https://www.stickermule.com/supports/wordcamps