I cut the circle on my table saw. Do this at your own risk as the table saw is a dangerous tool.. There are videos in youtube showing how to do this but anyway I'm uploading my photos here. I started nailing a nail at 62mm from the saw kerf in a small table saw sled. Then I cut the nail head and filed it to a point. I cut a 65 mm square from a piece of MDF and draw the diagonals to mark the center. I pushed the square center over the nail until it seated fully on the sled.