The very first day I started work (Piss off Chuff) a mechanic had removed a coil spring from a Renault, and put it in the boot of the car for whatever reason. The spring was still very much under full compression! while in the boot, the spring snapped, and tore a hole straight through the rear 1/4 panel, flew across the workshop out of the building via a reinforced glass window, never to be seen again! Over the years have seen countless incidents, usually with poorly designed kit that slips.. we now have a floor mounted hydraulic compressor, that seems to do the job safely.
Thom