The easy way is to cut your patch off the muzzle of the rifle. This is the only way I patch a round ball or anything for that matter. You will always get a centered patch doing this. You buy Cotton Pillow Tick at Wal Mart in the fabric section. I get the 100% blue strip pillow tick. You add your lube and set the ball under the muzzle, then take your patch knife and cut your patch off.

Otherwise get a chunk of one inch pipe. Sharpen the edges of the pipe with a file and use the piple like a Hollow Hole Punch. Set you fabric and then slam the edged pipe into a cutting board type material with a hammer. It should be able to cut the patch. I make all my own bore buttons this way....