In my room I have but one wall that could allow a desk but that wall is being used by my projector. I could still place a desk but the monitor would get in the way of the projection and I sure as heck don't want to mess with wires and moving a monitor out of the way every time I want to watch some TV.
Anyway. Two pictures are worth 500 words each :)
Step 1: What You'll Need.
1 8-12inch outdoor T-hinge. ($8)
1 1.5-2inch butterfly screw. ($.50)
1 fold-down desk. ($29 IKEA)
A few drywall screws.
Possibly 1 lamp that can clip to the desk. ($11 Office Depot)
And you'll need to locate a monitor that uses screws to secure itself to the bottom of its base.
Tap for threading metal.
Step 2: On to Construction.
It is 1 piece with nothing to break or malfunction. It is an outdoor door hinge that I bought from Lowe's for $8.
I had to place a 90degree bend in the long arm approximately two thirds of the way towards the base. This length may vary for you based on the thickness of the fold down desk you end up using.
That beautiful black finish is permanent marker. After a few coats it is nice and glossy just like the monitor's bezel.
2. Preparing the hinge for securing monitor: As you can see I had to place 6 drill holes. 4 on the base of the hinge to secure the monitor and 1 and 1 on both arms of the hinge for a butterfly screw that I use to adjust the position of one arm relative to the other.
The holes for the monitor base are easiest drilled after you align your monitor's leg where you want it on the thick arm of the hinge and using a marker to mark the spots through the monitor's factory drilled holes directly onto the hinge's arm (which attach the monitor to its own base). This way after you move the leg of the monitor out of the way you'll have 4 perfectly aligned marker spots as drilling guides. In this setup you are no longer going to need the monitor's original base so you can put it away after dismantling it.
The butterfly screw holes have to be perfectly aligned with the top and bottom arms so after I drilled one side (placing a folded cardboard spacer between the arms) I continued on and drilled through the other arm as well. Also, you have to tap the holes (create thread) used for the butterfly screw.
Step 3: Tapping and Securing the Monitor to the Arm of the Hinge.
So far none of the steps have had any real complication.
But since not every monitor screws into its base and some just fit into their bases without using screws you are going to need to locate a monitor that uses screws.
The perfect moniotor for this job is the 22" ViewSonic VX2255. It has a built in webcam and mic plus speakers which makes it a great monitor and just right for this project. I am sure some others will work as well. Before you purchase a monitor just go to a local store and glance at the bases. If it uses screws you are good to go.
Step 4: Recap
We have also placed corresponding holes on both arms and threaded them so we can use a butterfly screw as in the photos form previous steps.
Next you should be locating a stud on the wall you'll secure the setup to and drill and connect the long arm of the hinge.
The hinge should be secured to the wall about 2 inches above your fold down desk so that you can reach the butterfly screw.
I believe this completes the project and I hope that you give it a shot and enjoy using it.
My setup is over a year old and even though it may look not strong to some it is very solid. I estimate it would be able to withstand an earthquake of magnitude 8.85 to 8.90 on the Richter scale.