So while the patches are in the wash and drying, I’m building up the hole and thin area by more or less weaving new fabric over it. I rolled up a blanket and shoved it in the sleeve to hold everything open and flat and stable. Then I just went back and forth first one way then the other, making sure I was making it big enough that it went out to where there was solid fabric.

This wouldn’t be a suitable mend all by itself (it’s not dense enough), but I’ll be putting the knit patches over this once I’m done with this part, which will continue to build it up.