If you've bought the Brass-top or even Copper-top version you'll need metal polish and fine sandpaper as the metal parts are supplied as-cut and will need work to finish off.
You may also have received 'part rings' in place of the 3 thin rings, these are to provide a little extra ventilation.
Carefully sand the case top and bottom making sure not to scratch them, the side rings will be hidden so scratches aren't so much of a problem but the are fragile so don't put too much pressure on them.