Mountain Bluebirds

We have a pair of mountain bluebirds that keep eyeing the bird houses which are soon, hopefully tomorrow coming down.  So, this morning I spent a couple of hours building a "real bluebird" abode, sized to specifications in a book, but not what I would call a professional job, lol.  I hope I can get it hung tomorrow!  The reason I am anxious about this as a pair nested in the houses last year and the cats, of course got into them.  We saw the cat running by the big window with the bluebirds attacking her.  They were really mad!  However, sadly,  that ending their nesting in the bird houses.  I am hoping to be able to give them a nesting site in which the cats cannot bother them, and we will be able to enjoy their comings and goings and babies all summer or however long that sort of behavior takes.