@Terran:
1. Most of the rings are ice, however the more transparent parts of the rings are only player colliding.
2. I used a solid 'circle' scenery (used the pupil from ctf_eye) then went around it doing an outline of half of it. I then stretched where necessary to make it even and then duplicated and flipped it to make an even circle..
So Monsteri is sorta on the right lines, except I used a scenery once followed by flipping, duplicating and pasting entire rings.