Thinking that all out must have taken some time or your a genius gg
Neither; well... maybe the latter, perhaps.
The heavy shelving they lie on was already in the barn when we bought the property; as well as the heavy gravel sieves.
The bird door is merely half of a lightweight hollow door from the house remodeling progect.
The nesting box was already lying around somewhere out in the barn, but the solar heating windows were NOT installed yet. They are old shower doors from the bathroom redo a couple of years ago.
An early model of their heated area: