Thinking about hanging up four sets of Roman rings (gymnastics rings) from the ceiling in the children's room.
The house was built in 1991 and the ceiling is made of concrete elements that were lifted into place when the house was built. At least that's my educated guess since you can see clear seams in the ceiling every 3-4 meters.
What options do I have for attaching a screw eye to the ceiling?
My immediate thought is one like this with a plug:
The daughter had a punching ball in the basement many years ago, and it's been left there. Just unscrew it and let the expansion sleeve stay while you fill in with putty.
I use essve plugs with the right drill and their screws, and it holds like a rock. My projector has three screws, but I tried hanging from just one and it wasn't a problem at all... Concrete is the best for attaching things.