I assembled the shelf in the second bedroom so as to stay out of the way of the baby's play area.
I had already installed the back of the shelf in the cavity and thought that I would need to install a temporary brace to keep the shelf from racking during the move, but the shelf was rigid enough without the brace. I used screws for all joints and used dowels for alignment on the middle supports.
Here's a photo of the shelf in place before I attached the back, cut a hole for the elecrtical duplex, and secured it with some finishing nails.
My spouse wanted to see if the baby fit on the bottom shelf. He could if he curled up a little. I'm sure he'll be pulling himself on the shelf very soon!
Here's a photo of the shelf fully installed. We will be locating a land line phone on the second shelf from the bottom (you can see the duplex and the phone cable on the right).
All that's left to do is: stain, seal, and trim. We'll be using the same trim as the windows. Oh, I still need to connect the phone wire to the phone box. Maybe later today or in the next couple of days. Shouldn't be too hard.