I am planning on using the sport ball as a second tier.  How would I attach it to the 1st tier.so that  everything is supported?  Can't place it on a cake board--the board will be seen.  Sure could use suggestions on how to do this.

I cut a very small board circle for mine supported it with 2 bubble straws then one straw through the center to the ball cake. It held the weight may be worth a try

AYes, as cherries on top said, a small board. You have to trim a small amount from the bottom to keep the cake from rolling away. You can hide the board carefully with fondant, icing, or a border, just like any tiered cake.

Thank you both,  I will definitely follow your instructions.

I would also put a dowel through the ball, bottom cake & drum.  I use that or 3 dowels when I make my soccer ball cakes.  Good luck!

I'm thinking a 3 inch board.  Is that sufficient?  Also the 2 straws with a dowel through everything????? 

3" would be good just cut the cake a little to make it flat to balance.  Put 3-4 straws & definitely a dowel all the way through the cake & drum. 

What I would do is put the HOLE in the 3" board beforehand going from the underneath the board, then put a dowel into the cakes below & leave enough dowel extended above that will got through each part  of the ball cake but about 2" below where the top would be.  Put some icing on the board, put the cake on it, cover  with fondant & then you can just "slide" the cake onto the extending dowel without extra stress on the ball cake. 

If you need to decorate the cake when it is on the other cakes, put in the supports & center dowel, dust the top of the cake below then place parchment paper over the dowel & place the ball cake (with the cake board on top).  You can tear out the parchment paper when done.

Have fun!