I used 22 gauge cold-rolled steel sheet metal for demonstration purposes ... Follow the circle until you reach the end of the cut. Use a metal file to remove any sharp edges left after cutting ...

Pocket sheet metal gauge patented in 1878 and made by Brown and Sharpe Manufacturing Co., being a micrometer with a range of 0.0" to 0.375". Pocket sheet metal gauge patented in 1878 and made by Brown ...