If you have a door, say to your room, that won't close then this is for you. My room used to be a living room. Someone threw up some plywood and called it a bedroom. Except it does not have a closing locking door.
Now at least it closes and stays closed.
Print. Depending on how long you need your lever to be, print more or less "Lever Pieces." I used two knobs, 3 lever pieces, lever head, collar, collar minus arm, and latch.
All parts bolted together using m3 hardware, except for the knob bolt which is an m4 x 25mm. Design with those in mind as well. I drilled and glued the m4 into the knobs. I could have designed it accordingly, but forgot.