Steel is the classic material for building car frames — and there are several subtypes of steel to consider in building your own. 

Mild steel is a softer steel, with seams. Upon impact, it provides more give. However, mild steel is not approved for all types of racing by the SFI Foundation, so if you are planning on racing your car competitively, make sure you know the rules for the type of racing you want to do. For bracket racing, mild steel is okay.

High strength steel is probably the most common type of steel used in chassis construction.

DOM, or "Drawn Over Mandrel" steel has a smooth finish and high tensile strength due to the process by which it is made. Its weld line is nearly undetectable, so it is sometimes called a “seamless tube.”

4130 Chrome Moly is the most popular of all steels used for roll cage and race car frame building because it is extremely strong for its weight.

A new kind of steel, Docol®️ Tube R8, is even stronger (10 to 15 percent stronger than 4130 Chrome Moly). It is a Dual Phase steel that is one part ferrite and one part martensite. What it delivers above all is consistency. Variations in steel tubing can impact performance and safety; since Docol®️ is so consistent, it makes safety testing different builds and models easier. When you hit the road, you want to know the car chassis or roll cage you build is going to react exactly as you want it to.

Aluminum is also a light option for building a race car chassis. Companies like Tesla and Ford have begun using the material to make their car bodies. However, aluminum has some drawbacks — in addition to being expensive, it can be harder to work with and it isn’t as strong as steel.

Titanium is strong and light, but can be cost-prohibitive.