TheGodThings claims that the PrinCube is the smallest mobile colour printer on the market. Better still, the device can print on all surfaces and fits in the palm of your hand. The PrinCube costs US$109 and ships next month.
https://www.notebookcheck.net/PrinCube-The-world-s-smallest-mobile-colour-printer-has-raised-over-US-3-2-million-in-crowdfunding.443195.0.html