The frame is fabricated from 1 1/2" by 1 1/2" steel angle, with a wall thickness of 1/8". A friend, Dan Pate, has a great piece of metal forming equipment. So I tried this first. The force applied by his shrinker was so strong that it distorted the pieces to a point were I was not able to use them. It was just fun to see the process and to watch Dan use this great piece of equipment.