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 walls near the top to prevent heat buildup - Drainage — 4× 7mm floor holes, offset so they can't be blocked by nesting material - Mounting flange — back wall extends 70mm above the box with 6 screw holes for solid post or board mounting. Use a pole-mounted predator baffle for best results - Tool-free removable roof — rear U-slot straddles the mounting flange; two front locating pegs snap into blind holes in the roof. Press down to seat, pull up to remove. Clean out every autumn before birds return Print Settings

Material PETG or ASA — do not use PLA outdoors

Layer height 0.2mm

Walls 4 perimeters

Infill 25% (gyroid or honeycomb)

Supports None required

Body — print upright, floor on build plate, open top facing up Roof — print flat, smooth inner face down

Both parts fit on a standard 256mm bed with room to spare.

Assembly

- Mount the body on a post or board through the 6 flange holes (recommend 5–6ft height with a predator baffle on the pole) - Lower the roof straight down — the rear slot self-locates over the flange - Press the front down until the pegs seat That's it. No screws, no tools.

Placement Tips

- Mount in the most open part of your yard with clear flight paths in and out - Face the entry hole away from prevailing wind (east or southeast in the Pacific Northwest) - Near open water or fields is ideal — Tree Swallows hunt flying insects on the wing - Two boxes 15–20ft apart can host both a Tree Swallow and Violet-green Swallow pair simultaneously Files

- body.stl — box with integrated floor, entry hole, predator guard, flange, and pegs - roof.stl — shed-style tapered roof panel with rear slot and peg holes