I bought a new chair not that long ago and one thing that annoyed me about it was that the arms did not go far enough back. Long story short it was a good excuse to use my CNC machine. Made a few basic parts in Fusion and printed a test part for fitment. Tested it for strength and lets just say that I'm glad I have some thick Aluminum on hand. (3D print was only 2 walls so not that strong) Cut out of the final version 6mm Alu. Tapped ans installed.