This is a child safety lock / latch meant for use on sliding closet doors, or any other overlap-style sliding doors. Both pieces print easily and quickly without supports.
Very simple to install. Just use those 3M foam mounting squares on the backside of the body and stick it to the rear door. Make sure it is toward the top out of reach of the kids so they can't unlock it. Position it so that when the doors are closed the latch insert (when inserted) barely rests against the edge of the front door. (see picture for example. the doors are closed in the picture.)
Scaling / Modifications:
If the body does not fit between the gap between the doors, scale both pieces down until it just barely fits without dragging on the front facing door (to prevent scratching on the door). Likewise, if your printer flow isn't calibrated quite right the latch insert may not quite fit in the slot. If this is the case just sand it down a little or scale it down a bit and reprint the insert.
I printed my first version a year ago. Made a couple modifications and now here is version 2.0. It has held up to a my 2, now 3 year old trying to break into the closet every day for a year. This version 2.0 update is a change in the latch insert style, as well as increasing the overhand of the bumper on the latch insert to create more surface contact between the insert and the door. (this bumper extension is not shown in the picture of the printed example). In the coming v2.5 I will be adding a insert storage holder to go on the front door because I can't manage to take the insert out without setting it down and losing it ;)