Now lets see the materials needed:For mechanics-
1. One chassis (you can use any as of your convenience).
2. Four gear motors (I used 200 rpm motor).
3. Four wheels.
4. Female bolt (comes with gear motor).For circuit-
1. Two batteries- 6V 1.2A maintenance-free lead acid battery (you can use Li-Po too or only one cell, but it shoud be greater than 5V and have high current).
2. Wire stripper and cutter
3. Nose plier
4. Single threaded (hook-up) wires (multi colors).
5. One breadboard (174mm x 67mm).
7. IR-Photodiode sensor (if you can't find it, the ckt is discussed in this instructable).
8. Resistors- 270Ω, 10kΩ.
9. Capacitors- 10μF electrolytic, 33pF ceramic.
10. 11.0592MHz oscillator .
11. A burner for programing AT89S52. I have used ZF-007 ISP Programmer.
For IR proximity sensor:
1. Resistors- four 10kΩ, four 270Ω.
2. Potentiometers- four 10kΩ.
3. LEDs- four IR, four photodiode.
4. Copper clad board or blank PCB.