I have been ask, if I would like to come to an open door yoga day in our village and maybe selling some bags and other yoga equipment. Very kind to ask me, but I have no idea about yoga. So I started slowly and first made a very simple bag for transporting the mat.
The diameter is 17cm and you can put in a mat that is 65cm wide (what seems to be the normal size). I have seen that there a mats with different thicknesses, but 17cm diameter should be okay for all.
The bottom is made from synthetic leather to give stability and it's easy to keep clean.
It is also stable, when you open it and pull out or put in your mat. (I don't have a mat and had to put something else in for testing)
This is only a basic bag. I have some ideas for more advanced (and more expensive) bags. But first I have to show this one to a yoga person to see if it can be accepted.