Existing bathroom GFCI receptacle, I just removed the cover plate to check the wiring.
The receptacle is on a mirrored wall that runs from across the wall from counter to ceiling. The box is a 4X4 metal box with a two gang one device mud ring. However the box is recessed like 1-1/2" behind the mirror.
I would like to add a plastic box extender like this.
However, the hole is not wide enough to fit this box extender. It's close but the left side needs to be enlarged a little bit, shown below in red is what needs to happen.
What is the best way to give this mirror's edge a little shave?
I have an 4.5" angle grinder with a diamond wheel...but I think it's too large a tool and too aggressive if I slip.
I have a oscillating tool, but all my cutting blades are for wood, wood with nails, sheetrock/plaster, I don't have anything that will cut mirror.
Will a Dremel work here? A conical grinding stone or a cutting disc?
I don't want to crack the mirror.
The receptacle is on a mirrored wall that runs from across the wall from counter to ceiling. The box is a 4X4 metal box with a two gang one device mud ring. However the box is recessed like 1-1/2" behind the mirror.


I would like to add a plastic box extender like this.

However, the hole is not wide enough to fit this box extender. It's close but the left side needs to be enlarged a little bit, shown below in red is what needs to happen.

What is the best way to give this mirror's edge a little shave?
I have an 4.5" angle grinder with a diamond wheel...but I think it's too large a tool and too aggressive if I slip.
I have a oscillating tool, but all my cutting blades are for wood, wood with nails, sheetrock/plaster, I don't have anything that will cut mirror.
Will a Dremel work here? A conical grinding stone or a cutting disc?
I don't want to crack the mirror.