I've made a LEGO car with Caterpillar

I assembled "Tamiya Educational Construction Series No.100 : Track and Wheel Set (70100)" and attached them into the LEGO car I assembled last time.

I used 2 shafts out of the 5 shafts in the set. I connected caterpillar made of rubbers. I tried this set with my son, but this is more difficult than the slim tire set we tried last time.

I've made a LEGO car with double-gearbox and slim tire set

I made a LEGO car with the following two modules and a breadboard:

• Tamiya Educational Construction Series No.168 : Double Gearbox (Left/Right Independent 4-Speed)
• Tamiya Education Construction Series No.193 : Slim Tire Set (36mm, 55mm Dia.)

I and my son assembled the double-gearbox with 344.2:1 gear ratio. My son was saying "I like mechanical things". He looked enjoying assembling. We also attached the slime tire set. We used LEGO blocks to make the car body. We used blocks with a hole and inserted shafts. I connected the motor, breadboard, and battery box. By switching battery's plus and minus contacts, the car moved forward and backward.

I'm planning to connect the car into Raspberry Pi 2 so that it can turn left and right with various verocity.