I totally agree about the danger of springs, especially large coil springs - about the only automotive work I can think of that is worse is frame/body straightening with chain and "NOBODY" does that anymore. Think about the stored potential energy in that spring. If it can quickly accelerate a heavy car against gravity it won't have any trouble with saline filled cell membranes (your body). I make a fair amount of my own tools (want to make the Prechamber puller now) but I will never live long enough to get around to making a coil spring compressor. I've thought about it, but always dismissed it.