This controller holder is designed to fit precisely onto any Ikea Lack brand item. It should fit the lack coffee table, the side table, and the lack floating shelves. It fit pretty spot on and it quite sturdy for its purpose, so doesn't really require any additional fastenings. Not tested for anything heavier than a standard console controller. It works for me as is, but you could probably apply double sided tape to the inside of the face panel for additional peace of mind. Can't really apply to the inside of the top or bottom as that would change the spacing too much. 

There are two versions. The modern version is designed as right and left hooks that have a 34mm (1.32") space between the hooks, with a spaced divider on the upper portion that slots together, so that there is a smooth contiguous finish (excluding the seam). It also allows you to glue it as one unit if you want. The space between the hooks should fit most modern console controllers. The purple controller pictured is the 8Bitdo, and is the only one I've actually tested. If not, see second version. 

The second version is designed as two separate units, that can be spaced to however wide is required to fit any other controller or older controllers, such as N64 or GameCube controllers.