A quick scan of his idea was enough to show it would certainly work but wow it was complex however it set me thinking, how could I keep moving parts out of such a device, make it all but fool proof and easier to make. Simple ideas are best so I opted for a simple set of wedges that slide together maintaining the upper and lower surfaces in parallel, and when I say parallel I mean within .0004 (Four tenths of a thou, AKA not a lot) To say I was pleased with such accuracy is an understatement as it was a bit of an experiment.
The wedges, the slot in the top is for Nightforce 'scopes which have a spring housing for the erector tube on the underside of the body.
Rather simple and very effective, I checked ENS's AI for him and sure enough the ‘scope was slightly out of plumb, with this it was a matter of seconds to set the ‘scope. Simply slacken the screws off slightly so the tube can rotate in the rings with some resistance, slide the wedges into place with finger and thumb and squeeze them together whilst rocking the tube, once the tube stops rocking nip the screws up very slightly remove the wedges and torque the rings down, check once more by pushing the wedges back in and hold them up to the light.
Of course it does depend on the flat base of the 'scope being perpendicular to the reticle... Now the interesting part, would it work on a round top action without a flat surface to pick up on? Yes it does

One of those things I am rather pleased with, I can see myself making a few more of these in the not too distant future.
Thanks ENS for sparking my imagination, as he points out it is accurate, repeatable, quick, virtually unbreakable, super light and should last a lifetime, I even checked my AI with it this morning with the rifle lying across my knees.