To dream of a writing pen symbolizes that you have a gift for writing. This dream is asking you to create space in your life for writing.
A fountain pen indicates the same thing. In this case a fountain is a source, so a fountain pen implies that you are a creative writing source – an inspired writer.
A pen enclosure indicates suppression of feelings. You do not let your feelings out.
A play pen indicates the uterus – a place for a child to develop.