Today I built an extension cord with a switch. When the switch is one way, one outlet of the duplex is energized and when the switch is the other way, the other outlet is energized.
Now I know what you're thinking: "Who would do THAT? That's crazy."
And I'd answer: "HAH, CRAZY! I'm crazy? They called George Westinghouse crazy."
At which point you might say: "No one called George Westinghouse crazy."
And I'd say: "Well, they would if he tried to sell an extension cord like this!" And I'd be right.
Actually, I made it for our utility room, so that it turns on either the task light over the washer and dryer, or the LED strobe light we found at a thrift store a few weeks ago.
This all part of a program to try and deter rodents from entering our home. Turns out, the only thing that seems to repel (most of) them here in the East Mountains are flashing lights. So I have strobes in our basement, battery/solar powered operated Christmas lights in our (off-grid) garage, and flashing LED lights in the engine compartments and people compartements of our trucks.
Turns out Shelly also doesn't like the strobes, so we needed a way to ensure they could be turned off when we were in the rooms, but would come back on when we left. Since we had only single switches for the lights in the basement, I simply replaced those with three-way switches and wired in extra outlets that turn on when the lights are out. (Let the next owners figure that one out!) But since the overhead light in the utility room already had a pair of three-way switches, I couldn't do that. Experimented with a light sensing timer, but wasn't happy with the results, so I did this instead.
Tom