After welding the pieces together, we found the frame shrunk, so we cut it in half, and welded a brace to it. It isn't perfectly

After welding the pieces together, we found the frame shrunk, so we cut it in half, and welded a brace to it. It isn't perfectly level since the toolbox's bottom is kind of deformed. I suggest making the final 45 degree cuts after welding the first 3 pieces together.