A printer includes an array of rollers, an array of printing elements, and a positioning structure. The array of rollers is arranged in a first arc configuration to rollingly support a media web in a first orientation. The array of printing elements is arranged in a second arc configuration along the first orientation and movable relative to the array of rollers to selectively modify a space there between. Each respective printing element is aligned directly above one of the respective rollers to define a printing unit. A positioning structure is configured to releasably secure each printing unit at one position of a plurality of positions along the respective first and second arc configurations.