Instructions
Finding a Race
Decide what kind of race you want to take part in.
Study the rules of your race. Find out what kind of car you can and can't have, and what you would like to build for the race. Some racing bodies will allow you build a car out of found materials or any other objects you like. Some races, such as the official All American Soap Box Derby organization, require you build from specific materials.
Plan how you will transport the finished vehicle to the race location.
Building a Vehicle
Obtain plans. Download plans from the Internet, or your racing group may give you plans. If you get your plans independently, double check that they fall within the rules of your particular race.
Choose a division if you are taking part in an AASBD race. This decision will affect the type of car you can build. There are three divisions to choose from: stock, super stock and master. Each has its own rules for the type of car you can use and the requirements of the racer.
Gather your materials. Your tools will vary depending on how complex your car is expected to be. If you are racing with the AASBD, you will need to buy a kit to make sure you are within the rules.
Get Ready
Check the age restrictions. Some soapbox racing groups will have very specific age ranges, while others merely will have suggestions. Within the AASBD, each division has an age range from 8 to 17 years old.
Check your weight. Your plans likely will specify an ideal driver weight for the car. Again, the AASBD has suggestions for each division about the weight of the driver.
Practice racing. If you have friends who have built soapbox cars, race against them so you can both improve. Get to know how your car steers and brakes.
Dress appropriately on race day. You will be required to wear a helmet. Wear proper shoes for the race so you can steer effectively.