https://www.youtube.com/watch?v=73a_TNNGyI4
Safety in a budget racer, or any race car, is priority number one. That saying, "Safety Third," is best left to the backyard daredevils. On the track, though, you need a good roll cage. This particular build has to cope with a number of different rule books as the car is being built as a multipurpose racer.
In addition to the rule book, the cage design changes drastically if there will be a passenger as in rally racing. This is a fascinating look at the down and dirty of building a cage. And they sum up the proliferation of amateur welders perfectly: Welding is like photography in the mid 2000s.
Related: Starting a build with a $2,000 BMW is as risky as it is fun