Well, the world inside a Glowforge anyway! Having some scrap plywood I thought to make a 20-inch ruler that would define the space available and set accurate measuring points, I set Inkscape with a 1/10-inch grid and a snap-to-grid so they were dead on accurate and as I was doing it realized that I could not engrave or even cut the full length, so I measured a horizontal line as close as I could get to the max cut area, and cut the rulers down to that. I could not decide which side to put the inches so I made both the top one a hair longer to see if I could get away with it, and cut each one in turn.
As I then had two of them I measured the distance from front firewall to the back and cut the short one there so I could leave them both in place when cutting, and put on a coat of varnish, against any fumes, so I could wash that off.
So here (I hope) is the svg for both:
You will notice that the text is a bit odd as I had to score rather than engrave as the space available for engrave is much smaller: