To execute this build, construct an open structural box frame using one-and-a-half-inch square solid ash or birch timber rails joined with mortise-and-tenon or dowel joints. Fasten a solid three-quarter-inch plywood base panel and top panel to the perimeter rails to create sturdy horizontal load-bearing surfaces. Mill half-inch by one-inch vertical ash wood slats, spacing them exactly three-quarters of an inch apart across the side panels and front double-door frames using a wooden spacer jig. Secure each slat using wood glue and recessed brad nails driven from the interior side to preserve flawless outer faces. In the right-side wall, omit three consecutive slats to create an open seven-inch vertical entry slot for your pet. Mount the front slatted doors with heavy-duty piano hinges and magnetic push-to-open latches, eliminating the need for external metal hardware. Seal all exposed timber surfaces with food-safe hardwax oil to provide durable, water-repellent protection against pet stains.