Because I do many Amiga hardware repairs from around the country, I'm often sending lots of bare PCBs around.
As mentioned, the best way to ship the likes of Zorro expansion cards is to put them into a proper anti static bag. Then wrap it in lots of plastic bubble wrap and place it in a sturdy box. To make sure it doesn't rattle round, you can add bits of crumpled newspaper, polystyrene, cardboard, "peanuts", popcorn (environmentally friendly), or whatever.
Chances are you may not have a static bag that fits. In this case, wrapping with aluminium foil is fine.
When shipping bare motherboards, it's very important to remember the real time clock battery and circuit. Obviously aluminium foil and anti static bags have conductive properties, so can short out batteries. A direct short circuit, like with foil, can result in fire or battery explosion.
In this case, fold an A4 sized bit of cardboard in half, and place it over the RTC area so it covers the PCB on both sides. Use tape to roughly hold it in place. Then use the foil or anti static bags as you would normally.
Putting lots of fragile stickers on the package can help. The couriers interpret these as "break carefully" :-)
