Simple addition to a cheap laser pointer that makes turning it on accidentally less likely. Instead of pressing a button the user has to turn the switch to engage the laser, this also allows the user to leave the device turned on without holding the button.
The laser pointer I designed for has a round case with a diameter of 23mm and a round button of about 5.5mm diameter, this is a generic Chinese green pointer powered by 18650 lithium cell.

Update 08.02.2021: Changed design to press the button harder (mine started giving intermittent contact) and made the thing taller so it looks nicer and is easier to grip.