16. Make 12 sharp yellow pentagonal pyramids as shown, each using 1 ball and 5 long yellows. Notice that the angles between the yellow struts are all acute. This uses 12 balls and 60 long yellows.

17. Mount the 12 yellow pyramids to the medium blue pentagons as shown.

This is how the model should appear after you complete step 17.

18. From each of the new vertices just constructed, therse should be a natural way to connect five long blue struts. Do this, using a total of 60 long blues. Upon completion, you should see a very large blue icosahedron nearly bounding everything.