Measure the side of the quilt where the sleeve will be placed.”This one is 30″.

Cut a piece of fabric 9″ x 30″.

On both short sides fold the fabric twice, towards wrong side, and press.

Some thoughts:

The rod should not touch the quilt.

I usually use the same fabric as the backing to make a sleeve. I used one of the fabrics on the front of the quilt  so that you could see what was happening. If I had  used gray fabric for the sleeve, the sleeve would blend onto the quilt back and you would not be able to see where the sleeve was being placed.

Sometimes thick rods are used to display quilts, specially at quilt shows. This is why I bother to add a basting line, to add fullness to the side where the rod gets inserted and also to help me place the sleeve straight.