A drawer slider stopper, I wasn't able to find one for my drawer online or at any hardware store, so I busted out my calipers and got to work. This model took about 2 hours to print,. You may or may not need supports, I used supports with it face down (as saved), and it printed perfectly.

I printed at 100% infill so it is sturdy and is unlikely to crack. Other settings may make it even stronger, but I've been using it on 3 different drawers in my kid's room, and it has been working very well. It fit right in with a firm press, which is what the original part required as well.