Peter Scott wrote:
You would need to place the metal over something to use as an anvil,
and then centre punch where you want to start drilling. Failing
that, a U shaped notch would probably do as well - couple of snips
with string side cutters, wiggle the tab created until it fatigues
and falls off, then file to final shape.
lamp to sit on, and have the cable exit throug that.


I was going to suggest a slot, but in my experience wiggling to
fatigue the tab is likely to distort the metal that its attached to.

Peter Scott

Angle Grinder.
--
Adam