The ones that I have done are just a square of material, or a circle. I prefer the square, as it is easier. You can pink the edges. You place the flat lid on the jar, the put the fabric square on that, and screw on the ring. Tie a ribbon around it and you are done. Just be sure that you don't use it for anything that you need a tight seal for, as you won't get one.

Is this what you were thinking of, or something else?

I do the circle,cut with pinking shears,put it on with a rubberband to hold it in place,then tie a pretty ribbon on it.
Kathi