We used carrots, celery, grapes, and peas.
We sliced a few baby carrots and attached those to slices of celery. We used the other sliced celery for the legs and antenna on the alien. We cut the bottoms off of the grapes for them to stand up. I had edible eyes so we just gave them one eye with those. You could use anything for that..even cream cheese and a piece of a raisin. We put peas on the ends of the antenna and arms. You can just make a little whole in the bun and push in the peas on the ship. Very easy and it’s a good way to get your kids to eat their peas and carrots!