SocketSetStack
Socket set holders are unreasonably expensive for what they are and 3D printing is a beautiful example of showing your coworkers or spouse that a 3D printer is a powerful tool and money saver.
The parametric settings allow users to start with the default 1/4" socket size and scale up to any size they like. In fact, this will work with any square-pegged contraption you might have. The measurements are in millimeters, so remember 1" = 25.4mm
My day-by-day account, with pictures, can be found on my blog.
http://www.24hourengineer.com/search?q=%22SocketSetStack%22&max-results=20&by-date=true