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.