Printing apparatus (20) includes a donor supply assembly (30), which provides a transparent donor substrate (26) having opposing first and second surfaces and a donor film formed on the second surface so as to position the donor film in proximity to a target area (28) on an acceptor substrate (22). An optical assembly (24) directs multiple output beams of laser radiation simultaneously in a predefined spatial pattern to pass through the first surface of the donor substrate and impinge on the donor film so as to induce ejection of material from the donor film onto the acceptor substrate according, thereby writing the predefined pattern onto the target area of the acceptor substrate.