can anybody provide instruction on how to build the trap described here:
https://www.trapperman.com/trapperman/The_Weasel_Box_Set.html

Seems pretty self-explanatory! One 6' cedar fence picket/board will build one box. place a rat snap trap under the hole and go.

Respectfully, sir those are not rat snap traps. those are traps with notched jaws similar to a wolf trap, just smaller.

No, they are single longsprings. Not "notched jaw wolf traps" Please don't use terminology you aren't familiar with.

You can use a standard #1 or 1 1/2 long spring as shown, they do not have "notched" jaws. A snap trap works also in the same situation!

That same box will work for rats, mice, chipmunks, voles, and ground squirrels with a change of bait. Snaps being the preferred trap.

Swap in glue boards and you got a snake trap, particularly if well scented with rodent odors.

There should be dimensions all over the web, just build it to fir the "rat snap trap", that's what most use.
I could take a few pics of mine when I get home if you want.

Just use old first cut slabs of wood most sawmills sell it by the bundles. Trim all the pieces to the same width as evenly as possible if you’re setting on top of snow cover all sides if snow is not guaranteed just do the top and sides put a 1X2 across the bottom span for reinforcements. I’d leave the ends as they are you can use the same boxes for mink that way. Slots can be cut for 110s or 120s if you trim them that way to fit a coni then cut your slots for the springs.

Cheap easy cubbies that mimic a hollow log piece.