Allow the user to select multiple objects for protecting at once.

[WiIIiam278]

Perhaps by shift-clicking. May be useful to allow the user to select all of their protected things with a command, as well.

[Brianetta]

Will need a per-player set of Locations, rather than a per-player Location, to handle selections.

Commands will need to iterate over the selected locations. It will probably be a good idea to introduce an overt lock/unlock command, in addition to left-click.

Perhaps also a cuboid selection would be a good idea; shift-clicking a room full of chests or every repeater within a redstone contraption could get old really quickly.