You might find better luck making cookie cutters with your GF. There are few examples on here if you search (here’s one: Proofgrade 1/4" Clear Acrylic: Bunny Cookie Cutter)
There are a lot of benefits to the cookie cutter approach -first of all, it’s cheaper over the long haul than repeated cutting on your GF. There’s obviously the danger of PVC, which I believe most polymer clays are made from. Also, if your clay isn’t a consistent thickness, you’ll be forever tweaking the settings.