Mains Switch Cover

This is the only thing I have found that I can make that will actually sell.
It can't be patented, the idea was covered by a patent that expired a long time ago. I have made well over a hundred of these, they used to cost 25p each to make and sell very well on Ebay for £1. They don't tend to sell well above £1.
THIS IS NOT TO PROTECT CHILDREN.
THIS IS TO PROTECT EQUIPMENT FROM CHILDREN.
The design looks strange, but that is because I searched for information on every mains socket I could