I do it cause I enjoy it. Therapeutic perhaps.
Now... I do know this guy on the internet who cast his own headset lock nuts and machines them from scratch... but that's just crazy talk! 
Just kidding Otto- really it is an amazing job!
Today's ultrasonic haul. Screw the reusing funnel. New cleaner all the way. Life's too short. About three more drivetrains to go and my cogs will be clean. Chain's cooling off right now.
Gunk from the first chain go around in the cleaner. I don't do this every time, but this guy needed it.
A great way to kill time until taco dinner with the family tonight!