Hi, e!
Oh! I couldn't imagine why you posted about this word, then the light dawned when I thought to check the WAD.
You made a model of THIS? Cool! (By the way, I have been
extolling your virtues to someone lately--heh heh heh.)

I had to re-read your post to finally be able to picture
(I hope) what you were describing. I don't have a particularly mathematical turn of mind, and so I still can't picture what has happened according to the WAD's
second definition: "2. The remaining part of a parallelogram after a similar smaller parallelogram has been taken away from one of the corners."
Um--should I be picturing a parallelogram with two complete sides and two partial sides?