BE CAREFUL WHEN HANDLING A TRIMMER. WATCH YOUR HANDS AND ALWAYS WEAR EYE PROTECTION!

Edit: I discovered some major design flaws since play and inaccuracies add up from hole to hole. Over 10 holes I got a total width from 31.4 cm (37mm template) to 31.6 cm (47mm template) so the basic idea behind the concept seems to be broken.
For being able to use markings on the front I added a slot to allow more or less accurate positioning.
To get an exact distance of 320mm from front to back row I needed a 43.5mm template for the backside of my 400mm board. BE AWARE THAT THE 43.5mm TEMPLATE IS MARKED 43mm AS WELL!

I designed this as a kind-of drilling template for my laminate trimmer (Makita clone).
You can buy all sorts of drill-guides for 5mm drills to create a 32mm grid in the walls of a bookshelf but until now I found none to be used with a router and a template guide.
The first design is for 5mm studs (5.1mm hole) and a 20mm template guide (20.1mm hole).
Since my template guide didn't arrive yet this design hasn't been tested yet.

According to design rules of system32 one edge can be placed on the OUTSIDE of sidewall and gives 37mm distance, the other can be placed INSIDE and gives another 37mm distance (probably won't work because the router base will collide with the guide). Print a mirrored version to work in both directions.

If you need other dimensions or want to suggest improvements, just leave a short message.

I will add further pictures once I have done some tests with it.