I didn't have the time to complete 40 units, so I decided to do a tutorial for just a SINGLE UNIT. To put 40 units together requires glue (I recommend using a glue gun; it dries quickly). All you have to do is glue along the sides of the unit to form a sphere.
You can also use a needle and thread. To find out how to put together the kusudama with needle/thread, check out the Sea Urchin Kusudama here: http://youtu.be/QF2TsGGSerc
This is my first tutorial with narration. It was more challenging than I thought! ;-)
Have fun folding!!