Hi,
I want to build a shelf in the gap between a built-in closet and the door of a room. The shelf itself is a piece of 17mm plywood. One of the sides will be attached to the door frame. I was planning on attaching 42x19 pine onto the studs of the 3 walls, but the closet side has no studs. Will these drywall anchors do the job? I'm considering making a wooden frame with supports running down the middle, but I'm not sure if its necessary.

