Before working with your 3pi robot, I recommend the following things to help you get started.
- 4 x AAA NiMH rechargeable batteries. Other batteries will work, of course, but experience has demonstrated that NiMH batteries give the best performance and prevent sudden shutdowns. They are available pretty much everywhere that sells rechargeable batteries.
- White poster board is great for building courses for your robot. Folding grid foam board is particularly nice because it is easier to transport.
- Electrical tape is a must. And don't cheap out, either; get the expensive stuff. It is more likely to stick longer, especially when stretching it to build courses with sharp turns.
- A soldering iron is essential if you plan on expanding your robot.
Some general advice for the beginner.
- Make your 3pi programs print the battery voltage. You could do this before the program starts or while it's idling. You should consider charging your 3pi around the 4.8V mark. If your 3pi loses power while programming, it's toast.