Then use a plumb bob or a washer tied to a string to mark where you want to drill your holes. To do this, dangle your plumb bob from the ceiling above your rack, ...

Professional builders use a plumb bob to make sure their walls are vertical. Here's how. Measure two inches away from the top of your wall, set a nail, and hang the plumb bob. Let gravity draw the ...

For this purpose, you'd be better off using a real plumb bob, especially since the back of the iPhone isn't perfectly flat, which will throw off your results. Bottom Line: Looks great, but is ...