Here is another portable printer that lets you print on almost any surface. The Selpic S1 works on paper, cardboard, wood, leather, ceramic, metal, glass, and walls. You can print text, images, QR codes, and logos by sliding the printer along a surface.
The Selpic S1 can reach printing speed of 300mm/s. The ink is waterproof. It has 40ml ink capacity good enough for up to 900 A4 papers. You get 6 colors to choose from.