An elongate hand-held printer device for printing on a medium when a user moves said device over the medium. The device includes an upper and a lower moulding configured to complementarily receive each other to define a housing, said housing defining an ink ejection slot along, and a printhead module housed in the housing. The module has a plurality of micro-electromechanical ejection devices for operatively ejecting ink via the ink ejection slot. The device also includes an ink supply cartridge housed in the housing, the cartridge for supplying the printhead module with ink, as well as an optical encoder wheel to facilitate regulation of a printing rate of the printhead module as the device is moved along the medium.