The ones from Alibabba look quite alright. It looks like they are thick enuff to not stretch.
The ones that I bought were made. altho of very nice leather, had a habit of stretching.
Big pain in the butt. I had to wrap masking tape around the chalk to tighten them up so they wouldn't fall out of the pouch.
Brup, if you are planning on making your own, may I suggest looking at the thread that Chop Doc posted in re leather thread.
I had to fix several chalkers that were strung with heavy cord.
The cord itself, from rubbing on the back of your pocket will wear them out in no time flat.
Then, when everything lets go, you end up searching for all the little parts in the carpet of the pool hall.
I went to a fabric/sewing shop and bought a length of the leather cord.
Restrung them and have had zero problems wearing out since.
Just a thought.