That was the part i never liked when making these. When I was in 3rd to 5th grade every family member got a woven pot holder from me for Christmas those years. I made a lot for my grandmother, she loved them. She still had them in her kitchen and gave them to my daughters. The loops and looms available now are so much better. Have you used the free design wizard ?
https://friendlyloom.com/pages/potholder-design-wizard