Next, set the shelf on top of the monitor in the proper position. Press it down in front so that it is completely seated on the top of the monitor; there should now be a gap between the rear part of the shelf and the rear part of the monitor. Measure this gap and set the measurement aside until we are ready to cut the dowels. While the shelf is in place, mark the position of one of the dowels. Mark the underside of the shelf so that the leg will be about 1" (25mm) from the back and side of the monitor (note that this may not be 1" (25mm) from the back and side of the shelf because monitors typically taper in the back. Once you have one of the marks, measure its position in relation to the corner of the shelf and make another mark on the other side to ensure symmetry. Using a forstner bit, drill blind holes in the plywood in the locations you just marked. We recommend drilling about 1/2 to 2/3 the thickness of the plywood.