I have a pair of slippers that I bought from the Australian Geographic shop about 12 years ago. They are polar fleece with ribbing around the ankle and a heavy-duty synthetic fabric sole. They are only really suitable for indoor wear.
I wash my slippers from time to time and when I was hanging them on the line yesterday I noticed that there was a split in the sole. The polar fleece lining was still intact but I decided that I would try to mend them to prolong the life of my slippers.
Here is the slipper showing split in the sole.
You can see the zigzag stitching below.
While I was turning the slipper inside-out I decided that perhaps I will be able to make something similar. Polar fleece fabric and ribbing are readily available. It will just be a matter of looking for something suitable to use for the soles.
And this shows the stitching from the inside.