A childproofing lock to make it very easy to cleanly and securely lock a pair of cabinet doors that open away from each other. This only works if both cabinets have knobs with cylindrical posts/spindles. Look at the pictures and it'll become more clear what's going on. Sorry, but this solution is not for every cabinet in the kitchen or bathroom--it's only specifically for those settings where two doors open opposite each other.
You'll need the diameter of the two spindles on the knobs and the distance between centers on the knobs as installed on the cabinets (measure with the doors closed). The demo stl is provided only for illustration purposes: you'll want to use your own numbers to measure your knobs and your doors to customize the stl for your cabinets. The rest of the parameters in the customizer can be left to defaults to start. Click "open in customizer" above and you'll get a chance to input your parameters and print your custom-fit cabinet lock.
The main reason I invented this is because the ones you can buy in the store are ugly and awkward! I really appreciate feedback on whether this works for you. Please take pictures and post if you get it working! Here's a search for other products that I considered before deciding that I really wanted to make my own design.
I prefer to print in PLA because if you want to easily adjust the tightness of the lock you just run the elbow under hot water for a minute and bend it a bit tighter or a bit looser. I'm sure you can print it in whatever you want, though. And the parameters in the OpenSCAD file also help you tune it for how tight you want the lock to be / how easy you want it to be to release and re-engage.