I should've done a better job of explaining.
First, credit to imcarthur for this post:
http://forums.pelicanparts.com/porsche-911-technical-forum/357520-car-stereo-installation.html
The spacer fits behind the door panel on a 3.2 Carrera and gives you a solid surface on which to mount your speaker. You screw it to the door then screw your speakers (through the door panel) to the spacer.
I actually made 3 sets of these by hand and tossed all of them. The hand cut ones never seemed to fit properly.
nineball, I only rounded the U shaped cut-out but it's not hard to round all the edges. I'll wait a bit to see what responses I get.