I'm sure that this is not a Festool part - I've never seen this before and this doesn't look like Festool, this is a raw aluminium sheet, no finish on the surface, nothing.
Should be quite easy to do something like this "yourself" - a sheet of aluminium and a few drills.
You're right, Markus. I got the image from the Geat website that you pointed out on another thread. I'm going to try to make a couple out of some clear acrylic I have laying around.