This is a link to a Google 3D SketchUp drawing for nest box where birds enter through open front gable and drop down into box. Upper floor can be lifted out for cleaning.
Tag: nestbox
Tree Swallow Nest Box
This is a link to a Google 3D SketchUp drawing for a tree swallow nest box with hinged side allows access and is weatherstripped to keep out rain. You will need the SketchUp software to download this drawing and its freely available online.
Northern Flicker Nestbox
This is a link to a Google 3D SketchUp drawing for a northern flicker nestbox made with thick wood to withstand pecking. You will need the SketchUp software to download this drawing and its freely available online.