This 'able takes Piney's "Rasberry Pi Wall Mounted Google Calendar" and shows steps to mount the screen recessed in the wall. I found that any mount - even a low-profile mount - put the monitor too far out into the walking space. Since I wanted mine in a hallway area, I needed to recess it. Since I was already going to be making a hole to pull power, it seemed only logical to cut a bigger hole and recess.
Step 1: First: the hole
I started off by making sure there weren't any air ducts in the area I wanted to mount it. I did this by checking out the wall space above and below the floor I mounted the calendar on. Upstairs from it was a floor (not a wall), and downstairs in the basement there was a beam carrying the middle of the house, with electric wires snaked through. I was good to go.
I measured the dimensions of the back of the monitor - I didn't want to put the entire monitor in the wall due to its cooling requirements. I then carefully cut the drywall with a knife. Once I had the hole cut, I added wood bracing inside the wall - in order to get the wood to fit across the stud space, I cut the corners off the first wood piece so that I could knock it into place and screw to the studs. Then I screwed a thinner piece that gave me just the right spacing for the flat panel mount so that the monitor would be the right distance from the wall.
Step 2: Painting the inside
If you cut a hole in the wall that will be visible later, it's best to get some flat black spray paint and paint the inside of the wall cavity. I made sure I pulled any electrical wires first so I didn't get my hands full of paint later.
Step 3: Wire and attach LCD mount
I won't go into electrical wiring in this Instructable. Needless to say, follow code, common sense and always make sure power is off to the circuit you are extending. I pulled power from a nearby outlet and ran it to a box mounted inside the opening. I used a USB-wired outlet to eliminate the power adapter from the Pi.
I also added some drywall J-channel to finish off the raw drywall edges.