If you're careful, you could use ...
-- a nail
-- a piece of aluminum foil, rolled or folded for strength
-- a spoon
-- a fork
-- a metal paper clip, straightened out
-- a butter knife
-- a metal bottle cap with some paint scraped off
-- a staple, straightened out
-- a wedding ring
Any metal object can be used, since all common metals are
good electrical conductors.
You'd want to be careful, because they have no insulating covering
over them. If a piece of the conductor on one side of the light bulb
accidentally touched a piece of the conductor on the other side of it,
then the two battery terminals would be connected together through
a low resistance. There would be sparks where the two conductors
touched, the skinniest parts of the conductors would get hot ... maybe
hot enough to glow ... and the battery would soon be dead.
