craftymatt, I've never had any problem using the acrylic yarn. I've probably made some with cotton but I don't remember. The star design is automatically made when they are tied off. They just don't show up as prominent in the variegated hot pad. Here's a tutorial on how to weave them:
https://www.bing.com/videos/search?q...=0&FORM=VDQVAP
Of course your DH could probably make one. Our cousin made mine 52 years ago & he was in high school. I posted the dimensions of mine on post #8 on the first page of this thread. If you need any more dimensions just let me know. I think I covered all of them except the thickness of the plywood. Mine is 3/4" thick.