The entrance is bored just under 3.5 inches and set high near the roof line — wide enough for a screech-owl or kestrel, too small for raccoons, too high for a predator working from the ground. The size and height of that one opening decide whether anything moves in.

It is roughly 13 inches from the lip of the hole down to the floor where the brood sits. A raccoon’s arm can’t reach the bottom and a crow can’t lean in far enough. The deep ones raise owls; the shallow ones raise raccoons.

Untreated, unpainted pine — nothing else. Paint smells like a chemical alarm to an owl and bakes like a tin can in summer. Raw wood breathes, weathers to a soft silver-grey, and disappears into the tree.

One side swings open on a single fitted hook. A year of pellets and feathers comes out in about two minutes — no ladder-and-screwdriver fight. An owl passes over a box packed with last year’s mess; a clean one gets a new pair.

The inner wall under the hole is left rough, with low grooves cut across it by hand. Owlets leave the box before they can fly — on fledging day they climb that wall to reach the opening. A smooth interior strands the young at the bottom.

Every box is cut, bored, and grooved by Walt himself on a single band saw — most of a day of work in each one. No crew, no machine stamping them out, and no second batch once the bench is empty.