When assembled with the cups or hand pump attachment, Medela's breastpump bottles tip over and fall super easily. This is a snap-on collar to the foot that helps prevent that.

Prints cleanly without any support.

The cutout is designed to enable a bit of flex in the event of a tight fit, as well as to operate as a window if you align it with the molded scale.

Modeled in Onshape, view source here