This instructable will show you how I made my very own standalone retro arcade machine!
This is the easy man's way.
Features:
Hundreds of games
Many different consoles
Arcade controls
Easy!

Step 1: Materials and Preparation

List of materials:
(3) 2'x4' Perf board
(1) Computer Monitor
(1) Old computer or laptop
(1) Sheet of Plexiglass
(1) Piano hinge
(2) Regular hinge
(1) Extension Strips
(1) Arcade USB Joystick

Other materials:
Paint
Screws
Nails
Magnetic door stop
Fans & Cold Cathodes
Old computer speakers
Nuts/Bolts
2x4 boards

Tools:
Drill
Screwdriver
Hammer
Saw
Soldering iron

Step 2: Sides and Bottom

First decide how tall and wide you want your machine to be.
I made mine the width of the monitor so it sat flush agains the sides.

Set your monitor down and decide what angle you want it to be at.
Trace the angle of the monitor on a sheet of perf board. From here you can decide
how you want your sides to look. I had mine jut out of the top towards you, where I
put my computer speakers and the sign. I decided to make everything at 90 degree
angles, which helped a lot (minus the angle of the screen obviously, and the joystick panel).

Cut out both sides.

Step 3: Bottom and Top

Now to make the bottom.
Cut out your base and line both sides with 2x2's or 2x4's.
This is where you'll nail your sides on.
I cut the backs at 45's because I made a panel for the back bottom
where my power cord and USB extension come out.
I also didn't go all the way to the front of the board because I made a
little flap on the front to store extra controllers or a keyboard.

There's two parts for the top: The very top, and the bottom top (where the speakers go).
For the base of the speakers make sure you leave enough room to fit the soundboard of the
speakers.
Drill holes where the speakers will go.
Line the two sides and the front with 2x2's, leaving enough room in the front for the sign to be placed.
Do the same with the top.

Start nailing everything together.
I nailed an extra board to mount my power strip to on the back side pannel.
It will seem very flimsy. It will stiffen up with the monitor in there
and the back door on.

Step 4: Joystick Pannel and Back Door

Now for the top joystick pannel.
Figure out the best fit for your top pannel.
I had to angle the back of mine to fit flush with the monitor.
Lay the USB Arcade Joystick on the perf board, trace and cut out.
Make sure you don't cut too big or the Joystick will just fall through.
I cut mine a little smaller and sanded the edges until the Joystick fit
snug.

For the door you have a few options. If you are using a computer
I found the door is a good place for the motherboard. But you'll have
to mount a piece of plywood on the door so you can mount your motherboard.
I used two hinges to fix it to the side of the body. Added a magnetic strip to keep it
closed and a wooden knob i found to open it.

Also for mounting the monitor, I used two bolts with wingnuts for easy removal.
Once you place the monitor in, the body should be a lot less flimsy.

Step 5: Finishing Up

You're almost done!
Don't forget to paint it. I chose a matte black
and a light gray for the joystick pannel (SNES look)
2-3 coats did it for me.

For the sign I cut out a piece of plexiglass.
Then i cut a piece of vinyl and mirrored the image (I went with a Nintendo and Atari sign)
Place the vinyl on the plexiglass and give it a few coats of spay paint.
Once it dries, pick the vinyl off and you'll have a black outline with clear plexiglass
of your logo. I did this and put red cold cathodes behind it so the red shown through
the plexiglass.
I didn't screw the plexiglass in place because I made multiple interchangeable signs. Make
sure they fit snuggly.

I used old computer speakers that I found a goodwill for $2. Take apart the speakers
and throw away the casing. Mount the soundboard in the top of the body, behind the sign.

I also cut two holes in the top of the arcade where I placed two LED fans for cooling.
Make sure the fans face up to suck all the hot air out of the body.

Step 6: Software!

For this arcade I used an old HP Laptop that I had laying around.
I put windows 7 on it and created a visual basic program to select
each emulator and game.
The arcade is just a computer using a whole bunch of emulators.
For a list of emulators check out:
http://www.emulator-zone.com/

DopeROMs has a nice selection of ROMs.

For the visual basic script I just created a bunch of buttons linked to each game.
The game will open with the specified program.

This is the command I use:
System.Diagnostics.Process.Start("url")

Configure each emulator to use the usb joystick.

I also used a program called Joystick 2 Mouse to emulate the keyboard. I configured
the joystick to act as the arrow keys and the "X" button as the enter button.
I also used the L2 and R2 and Save/Load buttons and L3 and R3 as full screen and exit buttons.

Step 7: What's Next?

I have plans of re-doing this project and making it
bigger and better.
I will be building a full tower system with 4 player controls
using the I-PAC controller and actual arcade buttons.