The Multari

The first step was getting an Atari - I didn't have any 4-switch Ataris, which are most popular for cutting down to size. The only Atari I could get my hands on at the time was a Flashback 2, which can be hacked to boot from a cartridge.
As you can see, I desoldered all the unnecessary parts, like the power and joystick plugs.
The lower tan-colored board is my own cartridge emulator I wired in lieu of a cartridge.

Since it's really easy to get the game ROMs to boot straight off an EEPROM, I decided to use one... except I didn't have any usable EEPROMs, or even a suitable programmer! Instead, I grabbed a 128kB FlashROM from an old motherboard where it was the BIOS chip.
The board you see in the picture above is a general-purpose prototyping board I made last year, and the first one I had fabricated professionally. I wired the ROM socket to the I/O of a Cypress FX2, which is essentially a 8051 microprocessor with built-in capability.

To get the ROMs to fit on the 128K flash chip, I was limited to 2k/4k roms, so no bankswitched games like Asteroids. However, I still found more than enough fun ones.
Above is the software I wrote to concatenate all the 32 roms into one file, and pad out the 2k games to 4k. s

Here is the flash chip with its lower address lines wired to the Atari board. There is a PIC microcontroller which uses a switching transistor to turn the Atari circuitry on and off while it changes the game currently playing. It does this by simply outputing a number between 0-31 in binary on the upper address lines of the ROM.
The mess of wires is somewhat manageable because I used 30-gauge wirewrapping wire.

Now that I had the internals working, time to make the case! I drew a rough outline on paper and cut out a foam mock-up, which allowed me to see what I had to change.

Wood is fairly strong and easy to work with, so the case was created by stacking several layers of plywood and aligning them with dowels, for consistency. My dad is cutting the edges here in the photo.

The stack of wood would later be seperated and glued together to make seperate front/back molds.

The vacuum former from the L64 returns again, and I even used the same styrene sheet.
The first run was a failure, because the plastic shrunk while cooling and permanently froze onto the wood mold. I had to dremel the top off, and repair the mold with wood putty.

Here is the result, after I figured out how to slam my fist on the plastic to make the mold pop out before it cooled.

Fast-forward a few hours, and all the holes are cut, and parts ready to be installed. All the small holes were drilled in a drill press, everything else was rough-cut with my cordless dremel and filed to perfection (or at least as close as I could get it ;)

It was getting late, and I had a ten-hour drive ahead of me the next day, so I worked as fast as possible and put both halves together, with barely a half-millimeter clearance. The battery is a 4200mAh Li-Ion pack, Polaroid part no. BT41. The screen is the standard-issue LED modded 5" PSone LCD. Both were recycled from my L64 which I dismantled some time ago.

More pictures!