Assembled the Twin motor Tamiya gear box at a 203:1 ratio with my son. He likes assembling things.
Installed 56mm diameter Tamiya sport tires; hollow rubber similar to a RC car tire
Measured the overall width and determined that it exceeded the 100mm max width requirements for the mini-sumo rules.
Drilled all the way through the rims so that the axles could be pushed through (used a non-motorized hand drill). This reduced the width to 102mm. Will have to grind the ends down a little to meet specs.
Cut plastic sheeting to 100mm x 100mm with utility knife.
Trimmed to fit the wheel wells and affix to the gear box.
Purchased a Parallax sonar ping sensor and a light and sound kit
1. Configure Arduino for ping sensing and attach light and sound kit to get a visual indication of sound.
2. Purchase transistors and relays to create an H-Bridge for each motor to operate with the Arduino