I have several 2.3" holes in my concrete walls. I think they were likely used as part of the construction or assembly process. They're maybe an inch to an inch and a half deep, and they look like this:
I'd like to use them to non-destructively mount things to my wall (such as a VESA monitor, let's say). My idea is to put an anchor in them that can brace against the sides of the hole, then mount a rail to it that I can mount my monitor on.
The question is, what kind of anchor can I put in the hole that can non-destructively form a sturdy mount for a rail of some sort to mount a monitor?