You will end up with a square like below. (Use can use a L-square ruler to make sure it is square.)
Using an nail gun (or just a hammer and nails) reinforce the box in each corner.
You now have a finished wall cubby (or two in my case!)
Now we need to sand and paint it to look professional 🙂 Most likely, you will have some sort of a little gap where the boards meet. Use some wood fill to fill this gap.
Let it dry overnight.
Then sand it with 60 grit, 100 grit, and then 200 grit.
After two coats and a day of drying you should have two wall cubbies that look like this:
Install the hinges and you will have a frame that looks like this:
Next, on the cubbies mark where the hinges of the fake painting will meet cubbie. Make sure you give them enough room to close and line up on the cubby straight.
Now to attach the magnetic catches. These will make sure the frame on the front will stay closed.
Measure two inches to the inside of the cubbies.
You should end up with some finished Hidden Storage Wall Cubbies that look like this.
add a little wall decoration to the bathroom at the same time!