Light switch lock

I have many light switches around the house, many of them controls fans and lamps i don't want My kids to turn on/off so i had 3d printed more complicated ones before ,this time i want to create the simplest i can design and this is my first attempt .
Easy to print , fast ,took me 20 minutes to print. and it does work. You can use to keep switch on or off just by turn it over.