Valve Spring “compressor”

Me too. Had both lever style and pneumatic, neither strong enough for roller springs. Giant old c-clamp with a ring welded on the size of most retainers. Done.
I've also got a gutted stock steel rocker with a bar welded to it for changing springs on the motor. Rocker area that pushes on the valve removed, rocker now pushes on the retainer.
Thanks 33 for the motivation to make a way better spring compressor!