Wall Switch Lockout

thingiverse

I sometimes transform my basement into a darkroom and need a way of signaling to my housemates that they shouldn't try to flip on the light; this is how I do it. This can be printed as two parts: A sign you can attach to your wall switch. A latch (attached to the above sign by a hinge – use a 1.5mm pin for connecting the latch to the sign) that, when closed, prevents the switch it is attached to from being switched in either direction.