Umm. I would say if you asking if a 100amp flux core, 90 dollar welder will weld a roll cage, then you have no bussiness building one. But no, that thing probably couldnt weld anything. Flux core sucks for welding. And i would agree with an above post: you get what u pay for. Spend 350-500 on a decent little MIG setup, and when you need a cage, bring your car to someone that TIGs cages, and can get them certified if needbe. good luck man. Once you drop some decent cash on a decent MIG, have all the fun in the world learning on little stuff: exhaust, IC pipiing ect will be no prob for the welder, it will depend on you. Good luck man. Practice, practice, practice!!!! post some work when you done!!!