I used to be a professional mail order dealer and posted delicate items worldwide.
I discovered the best packing material is polystyrene chips.These are usually white curly things that keep their shape but remain soft to the touch.I found that many retail shops get stuck with sack loads of these chips and are or were pleased to give them away because it cost them money to dispose of by normal means.
I used to buy cardboard boxes in specific sizes which allowed me to post my objects with a mimimum of 3 inches of poly chips all around the object in the box. Wrapping the item in bubble wrap first increased its chances of survival in the post. Specialist firms exist supplying cardboard boxes and rolls of bubblewrap.
The worst packaging I experienced was a company in India who sent me an anglers willow basket wrapped in a bit of bed sheet with a lable sewn on it bearing the address and stamp.The basket arrived squashed and unusable.
Parcels are chucked about! They invariably have huge numbers of other parcels on top of them so a rigid container like a cardboard box is absolutely essential.
Underestimating postage is the biggest killer of enthusiasm.I once packed up 140 old tobacco and other tins in one massive parcel which cost £70 to post.Yes.Seventy pounds.OK, it was airmail to the USA.But still.Thats a lot of money.My customer refused to pay.That was 12 years ago.You can see after all this time it still bugs me!
I used to post lots of things abroad. Airmail I found was the best way to send things.(Dont forget to cover the parcel with airmail stickers) A week to 10 days was the average delivery time by air but the same destination might take a month or more by surface mail.Really heavy items are usually sent by surface mail so it stands to reason anything small could get lost or crushed under all the heavy parcels.Dont forget surface mail may involve your delicate item being in a 40 foot shipping container on the deck of a ship being tossed about in a storm!
I used to have an insurance policy just for insuring things I posted.I should think these policies still exist.