Lets look at this another way....the customer is trying to get something for nothing and she thinks this kind quilter will just give in by asking the quilt artist to feel guilty for asking to be compensated for her time, talent, and treasure. Tat is what this is. The customer is trying to take advantage of her. Period.
I would hand the scraps of the tailor fabric over to the customer and move on. Sell that masterpiece to someone who will appreciate it.
In the end, learn from this experience. If one does not have a business mind...do not sew for others.
I would bet that the mural artist gets screwed too but that is not our problem here!