i would use chromalloy its not as heavy as steel but not as strong its is stronger than alumminum ut a little heavyer so i would make the bars out of chromalloy
if ur gonna weld it ur self u might wana research welding diferent types of metals certain types of metal use different tempretures and different wire speeds
its not really about research its just getting a few scraps of the material you are ganna use and test different setting and see what works out best.... and depending whether your ganna mig weld or tig weld it.... and if your ganna be using shielding gas or not