This assumes that the covering inside and outside of the trunk is beyond saving.
First of all, remove the covering on the trunk. Inside is usually paper or a thin cloth. Outside is usually canvas, leather, paper, or metal. If it's metal, you would probably want to save it somehow as it's pretty hard to remove.
Find some thin sheet metal and patch any holes or eroded spots on the outside. These patches will disappear when you paint the trunk. Use the same type of nails that were used on the rest of the tin. Make sure that you hold a heavy piece of metal on the inside of the trunk when you hammer the nails in place. For several reasons: 1. To keep from damaging the wood, and 2. So that the nail "clinches" or bends back into the wood as it comes through on the inside.
Add new handles. Use care taking off the handle end caps because the nails have probably been clinched over on the inside and if you pull them out without first straightening them you risk damaging the wood.
You can also make a tray for it whether or not it had one originally. They are very useful.
Next soak the wood to remove all the glue, wash it off wipe it down and let it dry. Don't let it be wet too long because the thin wood will warp. Now comes the metal trim. Wire brush, steel wool, and sand as needed to remove any rust or loose paint. Now sand down the wood inside and out and vacuum. Seal the inside with several coats of urethane. Stain the outside wood. The slats are usually oak or some type of hardwood so stain them a different color than the body of the trunk.
Urethane the wood on the outside with satin finish urethane. Paint the metal trim and hardware using rust resistant paint. Reline the inside with your choice of paper or cloth.
Of course it's not possible to communicate many years of restoration and refinishing experience here but we wanted to give a basic outline of what needs to be done.
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