I wanted to make a key knob with a twist so I made one, literally. By turning against a resistance, it changes its state.

It's basically just a main body the key gets inserted into, an outer shell, an indicator plate and a lit. It does not fit every key or lock cylinder front but I include the f3d file so you can use the basic idea and make the necessary changes.

For the “locked” state, I just glued a red paper half circle to the indicator plate.

The main body and outer shell are print in place, the rest is separately while the indicator plate needs to be turn upside down.