However it may be different with Parcel Force, that's who delivered when I ordered Rad paint from Frost's via e-bay, that had a ball, which was clearly heard rattling away as it was just wrapped in a grey plastic bag, no bubble wrap or owt.
My packaging department advises me to tell you to pack them in a box with plenty of padding or bubble wrap, it's worth trying a magnet on one to see if it works. Extra cost yes but that's all part of P&P charges.
Bung 'em in the post but forget to put your addy on there for return address.
