How to package hatching eggs safely for shipment

[Titantherooster]

Hi all! I just sold my first dozen duck eggs on eBay! They sold in 10 min lol, guess I need to up my prices already. I’ve never shipped duck eggs before but wondered if there are any “tricks of the trade” to make sure they arrive safely and not only without cracks but also assuming this person wants to incubate that the embryo will be in optimal form?

 

[JacinLarkwell]

Do you have the foam holders you can send?

 

[UThobbyfarmer]

I've only been involved on the receiving end but foam shippers combined with box within a box has yielded the best results.