The gauge also doesn't stay square as the far ends veers off. A straight edge guide that doesn't stay straight isn't that helpful. If you click on the picture you can see how the gauge wanders off to the left. It's set at 90 degrees but just doesn't hold that well.
I also added a handle at the last minute to help with uses. It was just a scrap piece of 1x2.
I got his idea for a you tuber named Jeremy Pillipow who has a channel called Black Magic Craft and demonstrates how to make terrain to role playing games. I've learned a lot for that channel and recommend it highly. The specific episode that discusses a proton guide is here
You can also buy laser cut guides for the Proxxon tool from a EU based company called "Shifting Lands" It looks like shipping to the states is pretty expensive but his tools look amazing.
I plan on making a 45 degree guide with the remaining MDF but that's a project for another day.
Let me know what you think.