This is a sliding bracket assembly that will be used to hold up a light diffusion box for the ceiling. Its basically an enclosure box to put around a light fixture to make the light softer and less direct. I needed a way to attach the box to the ceiling, but with no visible fixings.

Two 'outer bracket' parts will be attached to the ceiling, then the inner parts attached to the inside of the box, on opposite walls. The box can then be slid onto the ceiling brackets.