||When I roll my mat up, the underside sort of pops forward (see the stripes). At first I thought about top-stitching to prevent this, but then I decided I liked the look of the contrast material, so I decided to leave it.
As for the straps, I went shopping for a bunch of notions at once and didn’t think to check on the size of D-rings. The pattern just says “D-rings.” You need to have them 2-1/4 inches wide. In my case, I had smaller ones and decided to work with them. So I folded my straps in half again and stitched them. That’s why my straps are narrower than the ones in the original tutorial.