I regularly go fetch coffee for my wife and I, they used to provide fairly decent cardboard carriers, but not they only have those awful ones that you stick the bottom of the cup into. They feel unstable, and for 2 cups are not much better than just carrying two cups.
So I decided to design a reusable carrier that I could leave in my bag fairly flat, but easily setup when needed.
The handle prints in place with the integral pivot points, the idea is that the handle can be inserted in the central cutouts in two orientations, one leaves it mostly flat, and one holds it securely for carrying. Hopefully the pictures show what I mean.
So far I've found that it works great with costa's paper cups, as well as their reusable cup along with a smaller glass 'KeepCup'
It obviously requires a cup with a taper to the sides, we do have one reusuable cup which has straight walls which obviously doesn't work with this design.
I printed with 2 perimeters and a faily low infill, it seems plenty strong enough to carry two full cups of coffee.
I tend to print quite coarse for utility stuff, though it might be nice to increase the resolution on the top few layers of the handle print to get a nicer grip feel.