I broke the derailleur hanger from a Trek 2200 after many years of hard use. This happened to be a terminal condition for this bike. Couldn't bring myself to toss it after so many wonderful miles - so it sat around my garage. Used the top tube and down tube for some other project a few years ago, which left the rear triangle lonely in the corner. I decided the triangle would make a decent shop stool, just had to make a few pieces and reclaim a seat tube from another spare bike.
Firs step cut out the rear triangle. This bike already had the top tube and down tube salvaged, I just needed to make a cut closer to the tubes. This happened to be a carbon tube bike, with aluminum lugs.