If you don't mind my saying so, you can use evergreen SOLID rod when scratchbuilding rollover bars and roll cages instead of tubing (hollow). Styrene tubing tends to kink when bent even with heat. With solid rod, it bends evenly without kinking (even without heat). When cold bending solid rod, just go slowly and overbend (i.e. if the desired bend is 90 degrees, bend to around 95 degrees) because the plastic has memory and will try to bend back to straight by itself. Of course, this tendency to "bend back" varies with the diameter of the plastic. The best way to bend styrene rods that I've found is to use steam from a kettle instead of a naked flame. Next best thing to use a small heat gun (see pic). Looks good!
