I didn't want to go with the easy Y is for Yellow option, or repeat 'Year of the Chinese Animal'. So I present to you a stamp where Heleen has used her own design. It seems like more and more post offices allow you to customize your own design. Here in the US this is licensed to a couple of companies (and you are charged extra for it).
I doubt any of these designs are truly collectible, but you never know. Heleen's envelope came with an added snail, as well as a fun December stamp.
Inside was a stripy banana - thanks for the fun mail, Heleen.