First, here is what you need:
Some cheap beans, plain and simple. They don't have to be navy beans, any type of dry bean will do!
A Styrofoam ball, really any size will do. Bigger beans probably should go on a bigger ball, but smaller balls go faster! This one is 2.5" and took me about an hour.
A trusty hot glue gun... and some extra glue sticks.
Pour some beans in a bowl so that they are readily accessible. Plug that glue gun in and get it heated up!
You'll want to start gluing the beans in a ring around the center of the ball. Some Styrofoam balls have a line around the middle already, mine didn't so I had to guess. Lay a line of glue across the middle of the ball; you'll want to work in about 1 inch increments so your glue doesn't get too hard. Taking one bean at a time, press the small end into to the glue so that the bean is standing on end. Continue doing this all along the glue line... and repeat! Continue working your way around, and continue to make successive rings around the ball.
Halfway done... if you look closely you can see all of the pesky glue strings :( You just need to pick those off after you're all done!
Now, you can also leave a small blank area at the bottom of this one... grab a stick, put the bean ball on top, and put a couple of them in a white urn.
Here is another, slightly bigger one made out of pinto beans: