YY Enclosure drill guide?

[MarkL]

I've had a YY enclosure for years that I want to use but I absolutely suck at drilling -- even when I draw something up on my own, I am always somehow off in my measurements.  Because this was a pricier enclosure, I really want to get this right and not putz around.  Does anybody have a resource for a drill guide for the YY enclosures?