Tree Swallow Birdhouse

Tree Swallow Nest Box — Cornell Lab Spec | No Supports | Tool-Free Roof A functional, field-spec nest box designed specifically for Tree Swallows (also suitable for Violet-green Swallows), built to Cornell Lab / NestWatch dimensions. Every feature has a reason — this isn't a decorative birdhouse. Why this design? Most 3D printed birdhouses are decorative. This one is built to actually attract and protect cavity-nesting birds. Dimensions, hole size, and ventilation all follow published NestWatch guidelines for Tree Swallows. Features 4" × 4" × 6" interior — correct spec for Tree and Violet-green Swallows 1.5" (38.1mm) entry hole — admits swallows, excludes European Starlings Chamfered predator guard collar — 55mm square collar with a 45° chamfered bottom face. Discourages cats and raccoons from reaching in. No overhangs = no supports needed Interior ladder ridges — horizontal ridges below the entry hole give fledglings grip to climb up and exit Ventilation — 4× 5mm holes in the side wal