My couch has two cup holders, but they were in bad shape and my son (8months) got his finger stuck in one of the gaps that were designed into it. So, I made a replacement holder for it! Its much more solid, stays in the hole much better, and best of all, has no surfaces that can get little fingers in it or leak moisture though the rest of the couch.

Base width is 72mm (2.8 inches) and depth is 42mm, so scale to whatever size you may need, though this does seem to be pretty universal with the ones I've seen.

I printed this with 6 layers, but that may be overkill, but feels very solid now. It will require supports for the top part.

This is my first design. Thanks!