Cut two pieces of felt, 6 1/2 inches wide (my case is pretty snug so if your glasses are large you may want to increase the size. ) One color for the inside and one for the outside of the case. I rounded the corners with a spool of thread - not necessary but I like the rounded edge look.
Cut out some leafy felt shapes and arrange them on the right side of the outer square, keeping in mind the square will be folded to create the case so the leaf design must fit on just the one half. After you arrange them in a way that makes you happy, glue them on with fabric glue. When the glue dries give each leaf a couple hand stitches.
Lay the outer square on top of the inner square and sew close to the edge all the way around, then fold the whole thing in half, right sides together, making sure your leaf design is where you want it to be and sew down the side and bottom of the case, leaving a nice size gap at the top to slide your glasses in.