Paint the round base black and let it dry, then add stars or stickers for decoration.
Paint each foam ball as a planet, adding light texture or color blending for detail.
Cut strings to different lengths and glue one planet to the end of each string.
Attach the strings evenly around the base, spacing planets so they don’t overlap.
Secure a hook at the top of the base and hang the mobile from the ceiling, adjusting lengths as needed.