Rivets.

Looking at ship rivets:

http://blog.liverpoolmuseums.org.uk/graphics/rivets.jpg

Most ships seem to use steel. For the model this would look ugly and it is unnecessary to use the same materials as used in real ship building. Brass or copper rivets will be used. On some of the ship the rivets are being sculpted and painted to look brass or copper. The rivets on the port holes will have to be copper as we cannot buy them in the right size in Brass.