This is such a neat idea from Baby Brainstorm! Your baby can experiment with things that are magnetic, work with one to one correspondence, and practice putting in and taking out all with one activity. Simply put a magnet in each spot and let your baby play.
An older sibling might have fun with this too. They can put the magnets in rows by color for baby or put pairs in the tin and practice matching. You could put the letters in and challenge your older child to find the letters of their name. Can they find the vowels? So many possibilities with such a simple activity!