Measure the width of the shelf board.,
Attach the wood supports.,
Attach the shelf board.,
Use this measurement to measure out two wood supports that will sit at a diagonal angle from the wall to the shelf board.
Cut the wood supports at diagonals each end, one for the wall and one for the shelf.
If preferred, cut a single but much wider wood support that will only be attached to the middle of the windowsill shelf.
, Screw the wood supports to the wall.
, Rest the shelf board on the windowsill and on the wood supports. Nail, screw or glue in place.
, Press on it gently to check that it’s firmly in place before kitty uses it. Then encourage him to give it a trial run. A few treats left on the windowsill can help to tempt your cat into place.