After purchasing cordless drills, saws, weed trimmers etc. one accumulates many 18 volt batteries and chargers--all of which end up consuming flat workspace. This instructable provides a way to move those batteries and chargers onto the wall.
Print the file with a 3d printer and hang the box on the wall using a wood screw.
Note that this is a 10 hour build on a Makerbot Replicator. You could build the same thing much more rapidly using plywood--but that's an individual choice.
Here's what it looks like with the battery and charger in place.