I keep my keys on a carabiner, which I keep clipped onto my belt loop. I often drop keys when clipping or unclipping the carabiner from my belt loop. However I frequently need to remove or add keys to the ring, so I don't want the keys to be too difficult to switch out. Hopefully this design works to my liking.

Update: After a couple days of real-world use, I've uploaded a heavier-duty version, and one scaled just a bit larger.