I learned to juggle 3 balls when I was about 10.  Its a great trick when you are 10 but it really comes in handy when you are a parent as endless entertainment for your kids.  But now mine are getting bored and they are demanding 5 balls.  Juggling 5 balls is pretty close to impossible.  But with a little technology, learning to juggle 5 could be easy.

What I want is a ball that is sturdy enough for juggling but can be filled with helium in varying concentrations.  Juggling a helium-filled ball would be something like juggling in low gravity.  Which means the balls would fall slowly and 5 balls would be easy.  With just the right concentration of helium, anyone could do it.  Then, the helium concentration is gradually reduced.  At each step, the difficulty increases just a little bit making it easier to master juggling the heavier and heavier balls.  Finally, its all atmospheric air, and you are juggling 5 balls in no time.