Not sure if you mean all of it, or just the carving part, but I used a 1" hole saw on a drill press in the small opening, and a 3" hole saw for the two larger rounds. Then spindle sand the edges. Then use a jig saw and chisel to clean up the small opening. Next is a router with a cove bit with a bearing. Then using a carving knife and carving gouge to get the shape. Hope that helps!
Time to buy a boulder to go in front of the window