Trying to make a climbing gym in my barn. trying to use real rocks as the holds. I figure I would have to have a rock hard enough that you can drill a hole in without it breaking. I also figure I will have to have certain type of drill. Any experts in here know how one would do this?

Use a high power drill like a hilti drill and and use a saw to cut the face off the stone at about 2 inches thick, anything less will be too fragile.

Good idea justin. A barn, you farm? I have a wall in my barn as well. Useful use of the space.