A nice touch to a childrens bedroom. This item comes with two files, with teeth and without teeth. Depending on childs age you won't want them hurting themself.
The size itself should fit a normal lightswitch, however, you can flip it 180 degrees in CURA and measure the underpart to ensure it fits nicely. It should be a few mm bigger than a usual lightswitch. It will and should fit tightly and won't be pulled off very easily. I have to use a tool because it fits my switch too well.
Any problems, drop me a message.