When you just can’t 3D print something as a monolithic part, you’re going to have to join pieces together. In such cases, most of us instinctively include threaded inserts or nut slots in the design, or even reach for a tube of CA glue. But perhaps you should be thinking more along the lines of heat-staking your printed parts together.
This is a companion discussion topic for the original entry at https://hackaday.com/2024/02/03/tricky-3d-printed-joinery-problem-give-heat-staking-a-try/