Need a little more information. What kind of fabric and what are you using it for. Most people just use scissors and cut the fabric too large. Then it gets folded to the underside of whatever you are attaching it to, so that it isn't seen. I presume you can't do this. But couldn't you just make a cardboard template and then cut the fabric with scissors or an exacto blade to the same size as the template?
What strange situation do you have that these normal methods don't work?