Packing materials are key. The goal is to keep the bottles from touching each other and make sure they are firmly in place. The box itself should be sturdy enough to withstand a drop or kick (it happens).
Minimum suggested materials:
- Gallon freezer bags for 22oz or 750ml beers
- Quart freezer bags for smaller 12oz beers
- Bubble wrap
- Packing tape
- Flat-rate shipping box
- Bathroom scale
Professional shipping containers like Uline pulp shippers or foam shippers are the best option. Boxes from online retailers like CraftShack can be reused as well. Packing is all about preventing breakage and if breakage happens, preventing leaks. Damaged, leaking boxes may be returned or confiscated by the carrier. Put bottles in ziplock freezer bags, use bubblewrap and tape to make each bottle spill proof, or use a large plastic bag that covers everything inside the box. Weigh the fully packed box by using a bathroom scale and taking the difference of your weight vs. weight holding box.