Punch a new row of 4 holes with the centers 1" from the edge. The holes should be 1 1/6". The should be every 2 inches.

Use a straight edge to draw a line 1" from one side.

Use a tape measure, punch, and hammer to make dents along that line at 2", 6" 10" and 14". Measure all the dents from the same side in case the plate isn't exactly 16" long.

Measure each dent from the side and the end after you make it, so you catch mistakes right away.

Punch out the holes.