The first thing you’ll want to do is cut open the top of the juice box. Put some rice into a sandwich baggie, squeeze out the air and seal it. I didn’t measure, just poured some in, but I would guess around 1/2 cup. Put the rice bag inside the juice box and reseal the top with tape.
Next, line the bottom of the juice box up with the bottom of the felt. Glue the felt around the juice box, leaving the bottom open so that it can stand well.
For the dude with the big tube on his head, you’ll want to wrap something around the top, I used chenille and trimmed the ends.
Another option is to fringe some hair first, before gluing the felt around the box. You can see I added a rectangle of felt to the top of the box since the hair won’t cover the top on this one.
Cut out some teeth, fangs, polka dots, stripes, whatever strikes your fancy and glue them to the boxes.