This is a child-safety outlet cover for 240 Volt outlets. I could only find 120 Volt outlet covers in the store but needed to cover one of the larger ones, so I made this.
The prongs actually don't quite fit - they bend a little when you insert it - which provides tension so that it stays in. If anyone else wants to remix this so that the prongs are sized and spaced perfectly, feel free. But this version is entirely functional.