8 Pcs Leather Circle Cutter Tool Set, Leather Punch Tool, High Carbon Steel Round Craft Punching Tools for DIY Craft, Punching Die Set, 8 Sizes 20 25 30 35 40 45 50 55mm

Maybe consider a different bag brand where the base of the bag is softer / more flexible. Check to see how smooth the edge of the hole you cut is. If your stoma is round, you could try a round leather cutting tool to cut the perfect hole. I got a kit from Amazon and use a plastic piece as a backing to prevent from cutting the bag. I slip the plastic piece into the single piece bags and use a piece of wood to press down on the cutting tool. The kit comes with several sizes so you can choose the best fit. I first clean the tool with alcohol to remove the oil and then spray it with the skin barrier spray to prevent it from rusting. So far it has help up well. I store the tool in a bag with a moisture absorber packet. https://a.co/d/0h6qx2PU