I made this simple homemade car project in Banjarapalya makerspace, its cool for kids for playing
I'm used laptop batteries for this car, you can use normal 9 volts batteries.
Water bottle caps for wheels
2 Laptop batteries
Hot glue gun
Step 1: Make a Whole to the Metal
You have to take a metal plate place it in the perfect place, im using good place on the land upon the steps because it is very easy to cut the metal, you need a hammer and iron cutter and mark on the metal plate how much toy gear wants the space for that after that cut the metal rectangle shape using hammer.
Step 2: Fix Wheels to the Metal Plate
I'm used 2 toy car wheels and water bottle caps for the wheels, take a small iron stick and fix the straw to the iron stick, after that you need to whole the wheels after that fix the wheels to the iron stick using hot glue gun.
Step 3: Fixing the Gears
Take a iron stick and fix the suitable gear to your motor and to the iron stick, after that take a gear fix it to the motor, fix it using the hot glue gun after that fix the wheels to the gear fixed iron stick.
Step 4: Giving Connection
Take a motor and take wires fix the wires to the motor to laptop battery and solder it using soldering gun, connect wire from motor to battery and battery to motor and take another wire and connect the wire from another switch to battery and check it once it has to be one switch for moving forward and another switch for moving backward, sorry i didn't take clarity photos.
Step 5: Fixing the Items
Finally you can fix the wires using tape or you can DIY after that your toy car is ready play.