For this, I was interested in the skin of the bat's wing and the veins you can see through the membrane. I wanted to exaggerate them and loop them into a graphical pattern on the wing. This brought me into google rabbit hole untill I found a lace bat. The wings are made of stiff black lace. So I copied that and as I sketch it with a pencil first I added my own idea. The hardest part is/was to make it symmetrical.
What I learned: A bat has a much more flexible wing structure. It is very much like a human arm and hand, except it has a thin membrane of skin (called the patagium) extending between the "hand" and the body, and between each finger bone.