What I did for a guide and since the rim has 5 sections, I divided that by 360 which give me 72. Now I divided that in half since if you create one half, you can duplicte it with a -1 on the scale as long as the pivot point is ok and it will make the 2nd half. so that give me 36. I created 2 planes as guides, one rotated 90 degrees and the other rotated 36 degrees. i took a sphere and gave it 30 sections which you will see will fit into the guide PERFECT. deleted everything but the 3 planes that fit in the guide that was attached from the center. I started from there and modeled it. Once finished, duplicated it, combined it to 1 piece. From there i made sure my piviot was at the tip of the rim in the middle and i did a duplication of 4 copies rotated 72 degrees and then combined everything that made 1 half. deleted the other half because it would have been alot more polies to combine and duplicated that site by a scale of -1 again to get the other half and finished. I know it sounds abit complicated but it was worth it