I've been asked several times about the hanging paper flower balls that we used as ceremony decorations, and the link to the tutorial is here and here on Folding Trees.com.
The directions tell you to you 3"x3" squares of paper but you can use other sizes, as long as the pieces are square. For the wedding kusudama balls I used 6"x6" squares, and I've also used squares as small as 2"x2" to make Christmas ornaments. Also, I just glued the ribbon to the inside of the ball, instead of running it all the way through and securing the end with beads/buttons. The other sneaky trick I employ when making these is to use paperclips as clamps. That way you're not stuck holding the paper petal together, waiting for it to dry. Once you have the basic idea down I would estimate making one ball takes about 3-4 hours. (Fortunately I had help from my mom in making the wedding balls! Extra hands make the process go a lot faster!)