A folding dog?

I saw this in the window of an empty building.  The words "folding dog" caught my attention and my mind began to wander.  I started to imagine a dog that could fold up, then saw the diagram and only then realised it was a box for a dog crate.  Way too much time on my hands at the moment.

The blue door photograph of two days ago is further down from a company that fits windows and doors, so I assume the space inside is used for storage.  Why was it painted blue when it could have been painted a drab colour to blend in with the brick work?