After watching the video with the link at the bottom I started thinking of a way to make something like this easily. My idea went from a little complicated 3d printed part to a simple part made from MDF. I thought about using a large metal L bracket of some sort, but those usually have a round fillet where it wants to be perfectly square to the corners. Are there any simple inexpensive metal angles that would work? That would cut out the use of the metal tape on that part. The bracket needs to be a little heavy so it does not move when the router bit touches it or you just need to clamp it in place similar to how he shows in the video. I have seen other people use the metal stick on tape since it has virtually no thickness so I decided to make a simple mock up of this idea to see how it looks. I also made a simple 3d print design to see if that is worth looking at.
Here is the video I was referring to above. BTW, the machine I will initially be using this on is using grbl.