I was looking for a multi-pen jig to use on the F1 but couldn't find one I liked, so I pieced together parts from a couple of DesignFind files and my own work to create a 3-pen using my P2S to cut the parts out.
This should be possible using a single sheet of 3mm Birch Plywood. I chose to add a second layer to my final product, but you may find you don't want to add it. I had additional scrap to use.
The larger piece has a pair of cleats that will prevent the back from shifting during operation. I added the F1 Base to further prevent shift during operation by gluing and clamping (for 10-15 minutes) the two pieces together.
I ended up centering mine with the newly reinforced base by lining up the 3-Pen Jig piece with the crosshatch (plus sign), gluing and clamping for another 10-15 minutes to be certain.