Works with an octagon too. You can keep on enlarging it till it reaches the desired size. I'm doing one for my round glass table and wanted one larger than the template I had.
I get plain white newspaper from the newspaper. They sell ends of unused paper each morning at the office. One I got should last me some years, it cost about 4 dollars or so and that was in 2008 when my daughters were visiting and we wanted something for little ones to draw on.