Blow up the balloon and tie it.

Insert it, top-down into the bowl.

We made a little plate out of aluminum foil to put the Mod Podge on. (You would also use a bowl or cup)

Spread the Mod Podge onto the balloon, starting at the top and working the way down about ¼ of the way down (or however "deep" you want your bowl).

Apply the leaves one at a time, applying more Mod Podge to each leaf as you apply.

Cover the entire area you want for your bowl.  Be sure not to leave any open spots.

Let it dry for a couple of hours. We let ours dry for about 3 hours.

Then, simply pop the balloon and carefully peel it away from the leaves.