On another thread JS mentioned getting machine paint matched by having it scanned. If a known set of machines, including over years of variations could be scanned then a database could be built up for identifying at least the probable manufacturere of parts like this. Trouble is it is seriously expensive. However if someone in a University history department were persuaded to do a PhD in the history of machine manufacturers then that might provide the resources.
One possibility coming out of that is to commit a murder leaving a scrap of paint embedded in the fatal wound…….