Ok, so I got all my bits cut out and assembled. Here’s what it looks like (without the intended blanket stitch around the edges):
Not sure if it’s quite what I was hoping for. Now I’m thinking using just regular cotton cloth instead of felt. I wanted it to be more supple and thinner, which is what I thought I could do with felt, but after the stiffening and the adhesive backing, each layer is about 2mm thick, making the whole thing 8mm at its thickest:
The quest continues! Stick around!