What is the best way to fill a 15mm hole in a plasterboard wall that was left by a "grip-it" TV mount fixixng? My regular filler (SF no-nonsense lightweight )just falls through.
Get a couple of "lolly sticks" put a small but long screw trough about 10mm from one end. Smear with grab adhesive, feed them both into the hole with the long tails in opposite directions. Pull both back against the board and hold for a couple of minutes. WAIT 24 hours, remove screws, fill and finish.
Cardboard with string is another way to stop filler falling through. Pull string to hold cardboard as you fill. Better way above though imo
Car body filler (or equivalent 2 part) is always good as it sets in about 10 mins. To bridge larger holes use some cardboard or similar for the first application.