For those that are curious, I've included the source code for Stinger. It's basically a knock off of Marauder's code, but ported to the AVR.

The Base is machined out of PVC. I happened to have some on hand and decided to try it out. The notch in the front was a goof where I didn't have the material clamped tightly enough during machining. The big holes in the middle are to allow air cooling of the motor drivers and CPU board. Bigger...

Here's a picture of the bottom of the base. The black circles are friction pads from Lee Valley. They help to slow the bot down if the front of the sumo goes over the edge of the ring. In normal operation, they don't touch the ground, but when the front goes over the edge, they come in contact with the ring. Bigger...

These are the GM-12 motors from Solarbotics, along with the custom motor mounts that I machined. By rotating the motors 90° they could be placed slighty closer together. Bigger...

These are tiny little metric screws (M1.7 x 0.35). I found some flathead ones from Spaenaur. They were pretty pricey and I had to buy 100. If anybody wants some, I'll sell them for $0.25 Canadian each. That basically just covers my cost to purchase them. I threw a quarter in the picture for scale. Bigger...

Here we can see the motors mounted on the base. The Motor Drivers are also from Solarbotics. The black tape keeps the battery from shorting anything out (some batteries have metallic casings). Bigger...

Here's all of the elecronics mounted. I'm using a MegaBitty which has an Atmel Mega-8 on it. I didn't install the H-Bridges that came with the MegaBitty and wired up the Solabotics Motor Drivers instead. The line sensor boards are MegeBitty Nano Line Sensor Boards. There are two slide switches, one for CPU power, and one for motor power. The orange rotary switch is a 10 position switch that I use to alter the starting behaviour. The black pushbutton is used for starting. Bigger...

Another view of the electronics. I removed the JST connectors from the GP2D12's and with a bit of bending 0.1" headers will fit nicely. Bigger...

Picture from the rear. I hate holding nuts, so I soldered the GP2D12 mounting nuts to the back of the board. Bigger...

Here's a side view. The wheels are machined from solid brass, with Synair polyurethane for added traction. I used the same mold that I used to create the magnetic wheels for Wedgy, so it will be pretty easy to use a set of magnets instead. Even with the solid brass wheels, Stinger only weighs 385 grams. Bigger...

This picture shows the battery position. I originally designed a pure wedge using Lithium Polymer batteries, but they couldn't deliver ennough current, so I switched back to NIMH and had to reshape the cover a bit. The battery is a Maha 9.6v NIMH battery that I purchased from Paul's Finest (which is located in Canada). Bigger...

Here's a picture with the cover on. I need to remake the cover and the sides to make them look better, but this will do for now. I put black electrical tape over some portions to make things harder to see. Of course, I left the front portion of the scoop bare, so that some robots will think that they've hit the white line and start to backup :) Bigger...

Side view of Stinger with the cover on. Stinger is only 1.25" high. Bigger...

This is what the opponent sees. Bigger...