This is a lid for a cup that snaps on to the top. It fits onto a restaurant 20oz Polypropylene "to-go" cup that are fairly common in my area. I made it so I could use some of my cups as general containers for storing solids(not necessarily water-tight).
This .scad file also models the cup itself, which is meant to be more of a mockup for virtual "test fitting" of the lid in OpenSCAD, rather than something that is intended to be 3D printed.
I measured a cup I had(photo of bottom markings above, for the curious) with calipers. I think my model is fairly precise with the exception of the bottom of the cup which has details that I didn't bother to model.