I love robots. Normally the ones I build are quite large and wouldn't fit in your pocket, but for a change of pace I decided I would try something small and fun! This robot is exactly that, and in fact fits inside of an altoids tin. It is inexpensive, versatile (so many different sensors can be used), and extremely entertaining. Check it out in action below! (Unfortunately I played with mine so much before I took any video I had used up my coin cell batteries and one motor started having issues, so I'm driving it with a 9V in the video)
Step 1: Parts List
Since this project is one that has many different possibilities I'll mainly discuss the essential parts.
1 x Arduino (preferably UNO)
1 x ATmega328 chip (other versions work too, more on this later. You'll most likely want one with a preloaded bootloader)
1 x 28 pin DIP socket (holds the ATMega, not absolutely necessary but you really should have it)
1 x 5v Regulator (L7805)
2 x 10 uf Capacitors
1 x 16Mhz Ceramic Resonator (a 16Mhz crystal works too, but you will need additional capacitors which take up space.
1 x pcb board (got a small one that fit in an altoid tin from radioshack for a few bucks)
1 x breadboard (to test the circuit)
2 x motors (I used pager motors with planetary gear boxes from robotshop.com)
2 x wheels (also got these from robotshop.com, but you can use whatever works)
1 x L293D (motor driver chip, which is necessary if you will be using motors)
1 x pushbutton (my code revolved around this thing, definitely useful)
Wires! Will need a lot to breadboard and solder.
Coin cell batteries (these keep the size small enough to fit in the altoids tin)
2 x photoresistors (lots of fun programs you can write for these)
2 x RGB LED's (gives it the personality!)
1 x mic element (lets it listen and react to sound)
Anything you think would be cool! I wanted to add sound, but sadly didn't have enough space left for a tiny piezo speaker.
Tools: clippers, soldering iron, perhaps a friend to help hold wires