This is a two pieces (per corner) 6mm standoff with a selection of mating glass clamps. The 6mm gap is to add insulation.
I have 1.3 mm glass which is a little narrow so I have wider clamps for it.
I have added clamps for 3mm as well.
This design is for long glass (picture frame glass). If the glass was the right size you might do it differently.
The SU has a few other parts I was playing with - single piece holders that didn't really work.
3D Printed, tested and in use.
I suggest printing in ABS not PLA because it will get hot.
Obviously overtighening may break your glass.
I intend to replace my Y-bar-ends with tapped versions so there is no nut to rattle off if the screw is loose.
Hint - under the standoff is a good place to pack up for minor bed leveling.
PS. I've added a nut replacement thing. I tap these to M3 but not all the way so the screw remains a little tight. I use them instead of nuts for the back mounts. The ridge goes up the side of the wooden bed to stop them rotating.