When fixing up a house or changing things around, it’s inevitable that you’ll have to patch some holes in the wall. Small nail holes are easy to fill with a bit of spackle applied with your fingertip, but bigger holes can be tougher, unless you know a couple of tricks.
The main problem with bigger holes is the spackle not sticking and falling through the hole into the wall itself. The way you fix that is by putting something else in first to hold the spackle in place before it dries.
An easy way to fill a medium-sized hole is to just poke a cotton swab into it. Push the swab in, let the cotton tip fill up the hole, then apply spackle over it. The spackle will adhere nicely.
For holes larger than a cotton swab, foam backer rod is a lifesaver. It’s intended to be used to provide backup for caulk, but you can cut short lengths of it and push it into holes to help spackle stick just as well. And if you have a really large hole to fill, you can cut lengths of the backer rod and place enough of them in the hole horizontally to fill the hole, then spackle over it.
A cheaper solution that often works almost as well is aluminum foil. Crumple up a piece of foil to fit, push it into the hole, then spackle over it.
No matter what you use for backup, let the spackle dry, then sand it smooth. You may find it takes several repeat applications and sanding to match the texture of the surrounding wall, but the whole process will go much easier with backing than it will by trying to fill a hole with spackle alone. Don’t ask me how I know.