Nails are needed to build and strengthen some buildings and objects in the game, as well as to complete Franco's orders. They are made of Iron in the Smithy. The Smithy will become available when going through the storyline on the Growling Grotto :)
Tinplate is made in the Smithy with the help of Iron and Orichalcum. You can make Pipes, Roof Tiles, and Ladder using Tinplate. Tinplate is also used to build the Carpentry Yard, as well as to complete Franco's orders.
Pipes are made in the Smithy from Tinplate and Co'balt. Pipes are used in producing Nuts and Columns. Pipes are also used to build the Polishing Yard, the Sculpting Workshop, and the Jewelry Workshop, as well as to complete Franco's orders.
Nuts are made in the Smithy from Pipes and Mi'thril. Nuts are used to make such valuable materials as Amphora, Jewelry Billet, Gear, and Prism. They are also used in building the Engineering Workshop, as well as in completing Franco's orders.