"Barrel" connectors

We have frequent need (many times each week) to match devices to
"suitable" wall-warts/bricks.  *I* do this with a dial caliber
and drill bits -- and a bit of math.
I need a scheme where "less skilled" (e.g., developmentally disabled)
folks can do this *reliably*.  Even if I have to spot-check their results.
I'm thinking of just buying one of every connector and mate, labeling
them, putting them on a "key ring" and then just having folks fumble
around until they think they've found suitable mates.
The downside is that there are cases where a connection may *appear*
to "fit" but isn't truly appropriate.  E.g., ID is a bit oversized
(or undersized, depending on your point of view).
Is there a better way?
Are there any other *mechanical fitting* issues that I may have
overlooked (obviously, there are electrical issues)?
Does such a prebuilt "kit" exist (nicely packaged, etc.) so I
can just buy a couple and save myself the hassle of making them?