you will still need to weld a bolt together frame......with mig you can have a nice looking weld and it can still be a bad weld......if youve got access to a mig get some scrap and have a play.DONT LOOK AT THE PRITTY BLUE LIGHT without a mask.....its a hectic first expieriance..pull the trigger youve got wire pushing out of the torch,alot of hot balls of metal dropping down your sock, not being able to see enough through the mask so on and so forth.....warped rails is the least of your issues......learning to weld will open up all sorts of interesting avanues and is a skill well worth having...but you arnt going to buy some steel and weld a frame on your first go with any welder