Updated: May 17, 2020
Here is a tutorial on how to safely and LEGALLY ship live, non-medically significant invertebrates. I will have packing instructions in caption under each photo.
But first: to legally ship live harmless inverts, you need to have a live animal shipping certificate through FedEx. Sounds complicated? It is. But not to worry! Companies like Reptile Express, and the one I personally use, shipyourreptiles.com, are certified through FedEx, and allows you to buy labels through them as long as you agree to abide by their guidelines.
You often get a discount off of retail rates, too. Live arrival guarantee up to $100 is an extra $2.5, which is well worth it. Now, the tricky part is finding a place that will accept live shipments. I learned that the hard way. The best way to do so, is to look up FedEx location near you on their website, and filter results for "dangerous goods". If an official facility accepting live animals is too far away, you can schedule a pickup through shipyourreptiles. They charge $5 for that service. And there ya go, the critters are on their way!
I've experimented with different box sizes, and I like 7x7x7 for larger shipments, but my standard is 8x4x4. I line it with styrofoam on all sides,and I'll go over how to make the lid in the next photo. If the styrofoam has a reflective side, the reflective side should face in. You can buy styrofoam boards in the insulation section of home improvement stores. With the box and styrofoam and heat pack or ice pack, I charge an extra mandatory $5 for the box to cover my costs in making them.
What foam insulation boards look like, from Lowe's.
This is what the lid looks like with the heat pack. I only use Uniheat 72hr heat packs even for 2 day shipping. It is the one that lets out the lowest and most even heat. The heat pack goes between the styrofoam and cardboard. The cardboard acts as an additional spacer to make sure the critters are not overheated. The styrofoam faces up. This can also be a side compartment.
Here's what it should look like when the lid is placed on top. The styrofoam faces up. The red line of the heat pack faces up through a hole in the styrofoam lid, or make sure it has access to oxygen for activation. Again, this can be a side compartment.
I use small soufle cups to put the spiders in. My standard go-to sizes are 1oz to 2oz, as those are sufficient for juvenile, and then for larger juveniles or adult jumping spiders respectively. Ventilation holes are poked all round and on top with a safety pin. The inside is lined with paper towel. I've found the top piece to be inconsequential unless the spider is an adult female with a large abdodmen. In which case, she needs extra cushioning.
Inside the box, it needs to be packed tight to reduce movement of things inside and to reduce how much the critters get tossed about.
I top everything off as evenly as possible.
The lid that we made earlier goes on top of it.
Here's what a packed 8x8x4 looks like. During times when I need a heat pack or ice pack, they are put in a side compartment, separated by a foam board divider, and taped into place. The heat pack may be folded upon itself, red-line outwards, to fit.