This is a wall mount for the Xbox 360 controller. The mount fits around the battery and is equipped with two 6mm holes for screws.
On the example picture it is fitted on a shelf with the help of a bracket.

I printed this with black PLA on a Mendel90 reprap with 0.25mm layer height, 0.8mm shell thickness and 20% fill density using Cura as a slicing engine.