OK, this is definitely not as easy as having the perfect template but it will work.
Take any square, relative clear template that is larger than 4.5" and mark off two sides of the square with tape. I often use Scotch tape that I place so that the middle of the tape is about where the exact measurement should be and then mark the tape with the exact measurement with a bright colored Sharpie pen marker.
To cut, pick your fussy spot, cut the two sides that the square template defines, rotate/move the template and line up your tape marks with the cuts, and cut the final two sides.
The problem with this method is that since you have to move the template, the final patch is more to prone to error.
When completely done cutting all of your squares, remove the tape and your template is good as new.