For anyone interested in Potholder style looms, I've run across another source. These seem to be particularly suited to weaving with fabric strips. They are being sold by Jennifer Ackerman Haywood of CraftSanity.
I also liked that she has them in several sizes. The placemat size seems particularly nice. Here's her backstory on how she decided to do this. (She also does an interview style podcast for anyone who is interested.)