I was running out of space in the hall to keep spare hard drives, so I put up a hard drive shelf. In order to achieve this, I used the wrong screws, applied those to the wrong hammers, and then carefully glued them into the wrong fasteners. It is level. It is mostly being held up by the pliant wall fasteners acting as springs. I used my splendid Bosch-PSB 1800 , which performed its role beautifully, injuring nobody.