I installed blinds in my kitchen.
I put the screws into the wall. The wall was plaster and inside it was a thin metal sheet.
The screws were 1/8 inches. So I drilled two holes of 1/8 inches through the plaster and metal and screwed both screws in.
I noticed that one of the screws didnt become tight as I screwed it in. So I drilled a 3/16 inches hole through the plaster and metal (through the metal I didnt have a 3/16 inches metal drill bit, I made do...) put a screw plastic cap in - with a lot of trouble, beraly fit - and screwed the screw into the plastic screw cap.
So just to reiterate, one screw is holding to the metal material (I sincerely hope) through a 1/8 inches hole. The other screw, is holding to the plaster and metal though a 3/16 inches hole (and a plastic cap).
Is this arragement, is it something that makes sense?