As for a little more detail about how they are made, I had pieces laser cut from thin plastic to serve as support for the openings. I would sew interfacing face up to the front of the face fabric along the lines of each opening. Then I would cut out the fabric within each opening, clip it, and flip the interfacing around to the inside. At this point I inset the laser cut pieces, and ironed down the free interfacing edges along the inside. I was happy with how they turned out, but it was a time consuming process.
Without further ado, here are the first, and last "samples" of that endeavor.