Ipswich, MA
The easiest way to determine the swing of a door is the hinge method. Open the door and stand with your back against the open hinges (not the butt of the hinges). If the door is to your left, it is a left-hand door. If it’s to your right, it’s a right-hand door.
Carefully drill holes for very long 1/2" hex-head bolts, then screw the bolts into the wall. Cut the heads of the bolt off and make sure that they are level and square to the wall. Then drill holes in the back of the shelf board and push it on to the bolts.
Gordon Harris 