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by Kniferide
Little late to the game, but I ran a shipping retail store for a few years in my early 20's. Quality cardboard boxes are exceptionally rigid, as long as they are packed tight inside. Rule of thumb, you want at least 2" around the entire item, and packed so tightly that it cannot shift or move at all. Also enough packing so that the box is tight to close up, taped well. If you can shake the package and hear or feel ANY movement, open it up, put in more packing until it CANNOT move at all. if you do this, that carboard box will be able to hole a tone of weight without crushing the box and your package will almost definitely get to its destination intact, even after UPS does their thing to it. 1 out of 100 packages I did insurance claims for were caused buy UPS mismanaging, they other 99 were denied because of insufficient packing.
As bad as they are, Styrofoam peanuts are the absolute best at packing the void in a box, because they push back when crushed. The Biodegradable version are not great, because over time, they flatten and allow the contents to shift. The large air bubble stuff is the worst because if it pops, you basically have an unpacked package that can be crushed easily. Sucks to se Styrofoam, but if you have something fragile to ship, its really the best solution. Pro tip, line the box with a large plastic garbage bag before putting in your item and the peanuts so that after the item is removed, the peanuts are already bagged up and easy to remove, save for another shipment. Also, wrap any electronics in bubble before pouring Styrofoam peanuts in there, if they do get crushed, they put off a lot of static, which isn't good for electronics, especially computers, ETC...
Sorry for the long post, but countless hours on the phone with UPS/FedEx, DHL insurance claims will make you a real snob about packing. They all will deny any claim if the package is deemed under packed.