It started with the new Mako MAM30 gizmo that provides a novel way of mounting a magnifier or other light weight optical device. Here is my 3x magnifier behind the Eotech holographic sight on the H&K USC.
It's not a QD mount, it just lets you move it out of the way, without leaving you with an extra piece of gear to juggle.
A spring-loaded rail lets you gently raise the device over the line of sight, yet keeps it handy if you need it again. It's permanently mounted, just out of the way if you don't need it.
After installation, I studied the setup with an eye to using the standard plastic "iron" sights as a backup. Of course, I'd have to remove the Eotech. No problem there, that's a given.
But with the Mako gadget clamped to the rail, the base blocked the rear sights. The whole concept was to keep things permanently attached, but out of the way when not needed.
I asked myself, "self, what would Dad do?". Since everything is made out of aluminum, he'd take ten minutes to what took me two hours: mill a sight groove in the base. After violating several of his rules for precision machine work, I clamped the block in a vise, and stuck the ball end-mill in a drill chuck, rather than using an ultra-precise collet.
After using some aluminum blackener to make things look better, and kill any glare along the groove, I had this as the final setup:
This was a simple project that is almost impossible to fail. And it actually works as intended. Remove the Eotech, pop up the magnifier, and the sights are ready to work. Aside from the feeling that Dad was tsk-tsking me about all of the unapproved short cuts, I'm very pleased with the device, and my modification.