Once the area on the two bricks is hollowed out, fit the saturated sphere firmly against the two bricks.
Using Cowee stakes, push them directly down into the sphere into the wet foam bricks.
Push several stakes in from different angles and cut the wood ends off flush with the sphere by wire cutters.
Longer wooden picks can be used instead of of the Cowee stakes. They have wire tightly wrapped around the ends
The underlying construction is so critical. Remember you'll be transporting this centerpiece, moving it around and you do NOT want it to come apart. Take care in the mechanics and you will be later confident that your flower designs will hold up to transporting stress.
Notice when I fill in the greenery that I take it right up to under the sphere, so the ball seems to be resting in among the ferns.
At first I planned for this design to have two smaller spheres staggered on the ends. I eventually decided (for transporting reasons) to create those spheres separately and cluster them close to the center arrangement once on the table.
So my largest table piece was this double bricked on, with the large sphere resting in the center.
I finished in the design with more leather leaf fern. I elected to take my flowers to the venue later and finished flowering and greening in the table on the spot. My time was at a premium, since I was not only the flower designer, but actually in the wedding as well. I had a lot of other pieces to finished, so I decided to finish my flowering on the wedding day.
That may sound complicated, but it is the construction of the pieces (what I refer to as "the mechanics") and the greenery that takes the most time. Taking buckets of flowers to the site means you can quickly cut off flower heads and tuck them into the greened arrangements very quickly. That way the flowers don't get bruised or broken heads en route to the venue.
Greenery is very long lasting. I took many of these pieces home and disassembled them - creating more flower tutorials after the wedding was over. It's the delicate flowers (freesia, stephanotis, spray roses) that you want to keep in your refrigerator and insert into your designs at the very last day.