My camping trailer has a nice (if cheap), through-the-wall, capped
entry/exit/pass-through for the power cord.

How should I make something like this for my house?

I occasionally run a hose from our grade-level laundry room, out the
attached garage entry door, to my RV or power washer. During this time,
the door is ajar for quite a while. I am concerned about vulnerability
to mouse incursion during this process.

Until now, I have used the doggie door as temporary pass-through for the
hose I use to pump-out the RV's holding tanks. This, too, opened our
home to potential mouse incursion. Now the dog is gone and the doggie
door is probably next.

A nice, easily "cap-able" for security and insulation, pass-through
would also work for an extension cord from a portable generator running
outside. I believe a cap like that found on the exterior of my RV, on
BOTH sides of my unfinished utility room wall, wouldn't be too unsightly.

When Qwest build a huge addition onto the Central Office nearby, they
replaced the standby plant with a HUGE generator. It was a total
rework. The generator contractor had pass-through, 4-inch diameter
tubes built through the brick-facaded structure. Through these
elevated, probably 12-inch long tubes, were run the cables that ran from
the trailered, dummy load outside, to the new generator installation
inside. This, I was told, enabled fine-tuning the new system.

Having such a portal at home would help with a couple of things I do
occasionally. One could keep the tube stuffed with old socks as
insulation during the lengthy periods of non-use. Ideas? TIA.
--

JR