I could not find a Plankton costume anywhere so I decided to make my own.
1. I used a round, pop-up clothes hamper, turned it upside down and cut holes in it for my son's head and arms.
2. I sewed a long tube (like a pillow case rounded at one end) to cover the length from the top of his head to the bottom of the hamper. Be sure to leave holes for the arms that match up with the holes in the hamper.
3. I cut an oval eye right where my sons face was and covered it with sheer yellow and red fabric. I used fabric glue around the eye since this would be a challening place to sew on a small machine.
4. I painted the mouth on with acrylic paints. Probably not the best for fabric but it worked and provided a really "cartoony" look. Be sure to put something between the layers of fabric so that the paint does not run through.
5. The eyebrow was cut from a half a piece of felt (folded the long way). I used fabric glue here again.
6. The antenae were very challenging and honestly they didn't even make it through the night. They were long tubes of green felt, turned right side out, and then stuffed. I fed a wire hangar through them to make them stand up. Like I said, we ended up taking them off 30 minutes out the door. The costume still looked good without them but if you really want them, I am sure there is a better way to do it.