The term 'metal holder' can be broken down into two words, 'RIVET' and 'ORE'. A RIVET is a metal fastener consisting of a smooth cylindrical shaft with a head on one end, which is inserted into holes in two or more pieces of material and then hammered or pressed to form a tight joint. ORE is a rock or mineral from which a valuable metal or valuable mineral can be extracted. Therefore, a metal holder could refer to an object made from ORE that is held together by rivets.