Saw these for sale online recently. And while I didn’t buy them – I wasn’t sure exactly how I would use them – I like the look. In black or brown they could turn shoes into something that looks like knee-height boots. Or you could do a Minuteman costume with them in a cream or white color. They are almost knee-height spats. Without the lace, of course.
You could probably make them out of any one of a number of things. If you were willing to put a seam up the inside of them, you could probably just buy a button-up sweater, cut the front button part out, and stitch it together making an inside seam
Anyway, I just wanted to save the idea here – for future use.