A drill guide uses a hole in a layer to guide a drill along an axial trajectory while permitting off-axis excursions of the drill during use. A number of such drill guides at varying heights from a target surface may be used sequentially or concurrently to enforce the axial trajectory in three dimensions during a surgical operation. A drill guide may include a hole in a layer that establishes a single point along the axial trajectory, or the drill guide may include multiple layers in a single device to establish two or more points along the trajectory while allowing off-axis insertion of a drill into the guide. The drill guide may be cuttable to accommodate intraoperative changes to the axial trajectory. In embodiments, a window or the like may be provided to permit a surgeon to view drill depth, drill orientation, the surgical site and the like during a procedure.