Laptops these days are so powerful that many people use them as their primary work or home computer. With this setup, you get the processing power you need, but most of us want a bigger screen. So we naturally purchase some wide screen behemoth monitor and hook it up to our tiny laptop. Problem solved - but it is such a waste to not use your laptop screen as a secondary screen and extend your desktop onto it. Then the real problem emerges - where to place your laptop? Some people just haphazardly shove it beside their main monitor. Some people stack it on a bunch of old textbooks. And some people go out and pay up to $150 for a fancy laptop docking station. I had a better idea. I made my own with an old monitor arm I had lying around. Total cost (not counting monitor arm) = $25.

Step 1: What You Need to Get Started...

The following is a list of all you will need:

3/4" plywood (good both sides). I had some spare cabinet-grade maple in my shop that I used (it has a really nice grain) - but any type will work. The amount of plywood you need all depends on the size of your laptop. My laptop is a Macbook Pro 13", so I built the entire rack from a 18" x 24" piece.
A VESA standard monitor arm. VESA means that it can be attached to the back of a monitor using four standardized holes. I had an old Fellowes arm that I bought at Staples. It is made of heavy duty steel and can hold a considerable amount of weight. If you would like to purchase it new you can find it here. It costs around $65.
A jigsaw with a brand new blade (for cutting plywood - I use Bosch blades that are specifically designed for cutting corners)
A few Quick Grip clamps or equivalent
The usual set of screw drivers
A mouse sander or other power sander. Personally, I love my little Black & Decker mouse sander for sanding small builds like this one.
Sandpaper for your sander as well as some to use by hand - you will want both low and high grits.
A Kreg Jig
Four Kreg Jig Screws 1"
Four #8 roundhead screws 3/4"
Four #8 flathead screws 1"
Three #8 flathead screws 1 3/4"
Three $8 flathead screws 1 1/2"
Oil based polyurethane (Minwax)
A natural hair paint brush
Wood filler (for mistakes - hopefully you won't have to use it!)

The cost of the actual building materials shouldn't be much over $25 providing you have your hands on an old monitor arm.

Step 2: Cutting and Prepping the Pieces

To build your laptop rack you will need to cut out four pieces. For clarity, I gave these pieces names (see pictures for more details):

Mount Piece - this is the piece that gets mounted to the monitor arm. The back of the laptop screen rests against this piece
Base Piece - this is the piece that the bottom of the laptop rests on. I added two tabs sticking out either side for all the laptop's cables (power, network, audio, USB, etc.) to rest on when connected to the laptop.
Footer Piece - this is the piece that supports the laptop's bottom edge
Lip Piece - this is the piece that extends slightly overtop of the laptop's bottom to secure it in place. It also has a cut away to expose the laptop's touch pad (just in case you need to use it!)

Some thoughts on this step:

The piece dimensions are displayed in the third picture. Note that these dimensions are for a 13" Macbook Pro. You will need to adjust the pieces to fit your laptop. I actually had my laptop in my workshop with me when I was cutting to make sure everything fit as I went.
All pieces are pretty straight forward except the Mount Piece which requires the bottom edge to be cut on an angle. The angle depends on what maximum angle your laptop screen opens up to relative to its base. A Macbook Pro opens to 45 degrees. This might be a standard across all laptops - I'm not sure, so check it on your own laptop before cutting.
You can do all this cutting with your Jigsaw, but make sure to setup a jig first. This is a fancy way of saying clamp a nice straight board down across your plywood and cut the plywood by running the jigsaw along the board. It guarantees a nice straight cut. It takes time to do it, but worth it.
When cutting any plywood you need to be careful to avoid the dreaded tear out. This is when the layers of plywood all splinters out and looks awful. When you are trying to make your creation look perfect, tear out can make you curl into the fetal position and weep. There are some techniques for minimizing tear out but I found the best approach is to use a brand new blade designed for plywood and to go VERY, VERY slow.
Always make sure your good side of your plywood (the side that will be showing) is facing the correct way. For a table saw the good side should be up - for the jigsaw the good side should be down. To determine this it is all about which direction the blade does the cutting - that's the direction tear out will occur, if it happens. For the laptop rack you ultimately want any tear out to happen at the bottom of the piece that is out of sight.
My design called for nice rounded corners. I used a little paint bottle I had lying around to draw the curves on my pieces and then carefully cut them out with my jigsaw (see picture). The trick is to steer your jigsaw by the base with your thumb as you cut. Be warned your thumb is uncomfortably close to the blade, so be careful! If the corner looks jagged after the cut is done, don't worry! You can sand it all smooth with your power sander.

Once the pieces are cut out it is time to sand:

Use your mouse sander and sand all edges until they are smooth (obviously) and you can no longer see any cut marks. Start with a lower grit and then smooth it with a higher grit. The inside corners are a little tougher so I sanded these by hand - It takes a bit of elbow grease.

Step 3: Putting It Together

Now onto the fun part - the laptop rack assembly:

Attach the Mount Piece to the Base Piece first. This piece is what is connected to the monitor arm so it carries all the weight. It needs to be nice and sturdy. I added three pocket holes with my Kreg jig and secured it to the Base Piece using three 1" Kreg jig screws. Since the Mount Piece is attached on a slant it is the trickiest piece to attach. You are going to have to experiment with your clamps to clamp it down as solid as possible in order to drive the screws into the pocket holes to secure it. (see picture)
At this point the Mount Piece will probably be a bit wobbly, so to make it solid as a rock I added four 1" flathead screws through the bottom of the Base Piece up into the Mount Piece (see picture). Be sure to drill pilot holes and counter sink.
Attach the Footer Piece to the Base Piece using three 1 1/2" flat head screws (pilot holes and counter sink).
Attach the Lip Piece to the Footer Piece using three 1 3/4" flat head screws (pilot holes and counter sink).
Note that both these sets of screw heads are somewhat hidden from view when using the laptop rack.

Step 4: Polyurethane It

This is my least favourite part of any build. It's literally as exciting as watching paint (or in this case polyurethane) dry. Some thoughts and tips:

I have finished many of my recent projects with oil based polyurethane (semi-gloss). Not only does it add a nice layer of protection to your build, but the oils soak into the plywood giving it that nice tanned look. I like the look so much I have pretty much abandoned staining. Of course, you can stain your laptop rack any colour you wish prior to adding polyurethane.
Be prepared to put three coats of poly on your finished laptop rack. Use a natural oil brush for this (a new one is best) and have a flashlight on hand while you stain to inspect for drips. I find that even in a brightly lit room it is sometimes hard to spot drips. If you miss one and it dries you are stuck with an ugly hard lump on the surface.

Step 5: Attach the Monitor Arm

The final step is attaching the monitor arm to the Mount Piece of the laptop rack:

Lay the VESA standard mount of your monitor arm on the back of the Mount Piece. If you followed the dimensions listed earlier there should be lots of room for it. Center the mount perfectly and drill four small pilot holes through the VESA holes (see picture).
Use four 3/4" round head screws to mount the monitor arm to the Mount Piece

Attach the monitor arm to your desk near your primary computer monitor. Drop your laptop into the rack, hook up all the cables, and you're finished!