I work with mixed media and sometimes I need to find the center of a disc. If I made the disc myself, it was laid out from the center, but if it's say a round baking pan or a lid, I need to find it.
Step 1: Methods and Parts
One method of finding the center is with two squares, but that takes alignment, coordination, and the aforementioned two squares. Another method involves a compass to make several smaller circles and draw lines through their intersections. Yet another method involes drawing tangents, which are square to each other and then connecting to corners diagonally. Worst of all ... equations ... yuck.
Anyway, my solution uses plywood and hardboard (of course).