That is rather good, it is what I call 'fiddly' things, I'm not good at, memories of my mask attempts.
I have bought some leather on Ebay, can't remember what for but it is quite good if you want to hold something tight and want a grip (don't ask). I did try sewing it though, just to see, a bit later and with my Pfaff Expression it sewed through fine, even I was surprised. I did put the teflon foot on though.