I have a very irregular shaped ileostomy stoma plus developed a stomal fistula in a v shape on one side. Cutting the opening on the wafer to fit was beyond frustrating and my skin was suffering greatly. So was my mental state.
I used the stomal measurement guide and chose a size slightly larger than the stoma. I took a picture with my phone. I then enlarged it so the circles of the measuring guide matched, so it was true to size. I took a clear piece of plastic and traced my stoma.
It's been an emotional and physical lifesaver after weeks of getting it wrong. And eakin seals by Convatec have been a Godsend.