Electrographic printing apparatus for forming a toner image on a recording medium includes: a magnetic brush having a rotatable magnetic core and a stationary outer cylindrical shell; a developer supply for supplying a magnetic developer powder to the magnetic brush; an array of microchannels on the outer shell for forming a plurality of parallel lines of developer in the channels; means for selectively transferring developer from the lines to a receiver; and a receiver electrode arranged in spaced relation to the array of microchannels to define a recording region through which the receiver can be moved.