After the campaign ends, you choose which unlocked designs you'd like a sticker of! Stickers are matte, and about 3 inches (7.6 cm) long.  

By default, these will be sent in an untracked, stamped letter envelope (included in the base price). Can be mailed internationally. Tracked shipping may be purchased separately at the end of the campaign. 

I cannot mail to USPS prohibited or restricted destinations. https://pe.usps.com/text/imm/immc5_002.htm