Make them out of either 2" x 2" or 2" x 3" RHS tubing. Go with a 3-4mm wall section. It is pretty straight forward job if you are handy with a welder. Some guys will make a template and cut them so the fiaganst the floor pan. Others will do the cut through and weld them as has been suggested. Depending on the method, there is a haf to full days work in them.