For as long as I have been living here, I have had a minor problem with
cats opening the cabinets under the sink in the master bathroom and
getting inside.  I say minor problem because I keep the door shut except
when I'm taking a shower (I use the back bathroom for most everything
else) and all I had to do when done was open the cabinet doors and chase
the cats back out.  Then CJ refused to come out one night and I didn't
discover him until the next night.

Sometime buring his imprisonment, he found a small hole in the wall
between the bathroom and a closet - the incoming telephone wire comes in
under the water heater and runs through that wall into the closet where
there is a wiring panel to split it out for the several locations.  That
cat enlarged the hole so then I had to chase him out of the closet after
chasing other cats out of the cabinets.  The kicker is that closet is
where I store the spare cat food: two twenty pound bags of it.

Since the last thing I need is a cat opening those bags if he gets locked
in again, I started blocking up the hole.  This turned into a sort of arms
race: I would block the hole; CJ would unblock it; I would try something
else; he would unblock it.

Several years ago, I purchased a bunch of childproofing kits to do the
upper kitchen cabinets (Snowball likes to get in them and push stuff out
until she has a nice nest made), but discovered that they don't fit my
cabinets.

Well, a couple of weekends ago I dug them out and *made* them fit.  Now I
have to push the new latch clear through the partial opening, but the cats
haven't figured out how to do that ... yet.