There are times when you need to cut or fill an area that doesn’t consist of nice squares or rectangles. I faced such a situation when I was installing radiant floor heating in the townhome that I’m renovating. In that situation I had to create a subfloor out of puzzle pieces of OSB wood. This left some unusual spaces that needed to be filled in. The easiest way to do this was to create a cardboard template and then use that template as a pattern to cut out the OSB. See the photos below.