4. Make 20 trihedral rosettes as shown, each comprised of 1 ball, 3 long reds, and 1 medium yellow. Notice that the angles between the reds must all be obtuse, and that the yellow strut lies on the line of symmetry inside the cone spanned by the reds. This uses 20 balls, 60 long reds and 20 medium yellows.

5. Mount each of the trihedral rosettes onto the small stellated dodecahedron in such a way that the long reds connect to three of the vertices of the small stellated dodecahedron and the medium yellow connects (quite naturally) to a vertex of the dodecahedron from step 1. After attaching all 20, you should see a large Y3 rhombic triacontahedron (30 rhombii) bounding all the pieces.

6. Make 30 squat pyramids as shown, using 1 ball, two long yellows, and 2 medium reds. This uses 30 balls, 60 long yellows, and 60 medium reds.

7. Mount each pyramid from the previous step to one of the red rhombii of the rhombic triacontahedron. At this point you should notice a similarity to one of the final stages of the Zome model of the 600-cell.