So when it comes to souvenir pins and buttons I am always surprised at the range of items out there. One item I have recently been made aware of is Ship Launch Pins/Buttons.
It would appear when a ship was launched at the launching ceremony Pins were given out as souvenirs or they may have been used as a form of a ticket to watch the ceremony.
Most of those I have seen are from the World war 2 era. They are about 1 1/2 inches.