There are many different ways to successfully pack and ship widows, so I'll try to cover a couple briefly and one in-depth.
(1) The first (and probably easiest) method involves a simple deli cup (shown below) with some paper towels. The only drawbacks of this method are: space and time. Space- this method will take up so much more space inside the box than a simple capture tube. You will only be able to fit a few cups inside a normal-sized boxed. Time- more so with this method than the next, the spider will need to make a web in the cup which takes a bit of time and energy to produce strands of web. Not too big of a deal, but if you need it done asap, pass on this one.
Shown below is the type of cup I'm talking about. You can use any size, I prefer the shorter version of this, but either will do:
Take this cup, and make sure it doesn't have anything else inside (no dirt or sticks! These will just get jostled around and potentially injure the spider!). Take a single piece of paper towel and line the inside (imagine you are wrapping a baseball). Simply place the spider inside the paper towel and s/he will build a web, stabilizing the spider throughout the journey.
(2) The next method is the one I use when shipping lots of spiders. This one takes up hardly any space in the box, which is great because you can stuff tons of spiders in a single and inexpensive box. The only drawback to this method is time: time in the way of preparation.
Materials you will potentially need: 1) tube (any size will do. Something around the size of a pill bottle is ideal. The little dram vials (like this one) are absolutely perfect for this. But so you could see what was going on here, I used a slightly bigger vial/bottle than I normally use.), 2) toilet paper (the fluffier the better!), 3) 1 or 2 sticks, 4) catch cup (make sure it's clear! Once you get the spider out of its old enclosure, you might need a catch cup if it decides it's going to make a run for it), 5) a syringe or a way to drip some water (not pictured. yet.). Here they are:
First step is to line the inside of the tube with toilet paper. This will put a little bit of padding between the rigid walls of the vial and your spider's fragile abdomen. Ruptured abdomens from rough handling is one of the biggest (and realistically, the only) concern when shipping your widow.
You can do this several different ways. You can use a finger, or do what I like to do and find a thinner tube than the one you're using and wrap that, like this:
Shove it down into the tube, and leave a little bit of room at the top. It should look like this:
Next, loosely wad up a small piece of toilet paper:
And place this at the bottom of tube. This serves 2 purposes. 1- it pads the bottom of the tube for when the box gets thrown/crushed/slammed/kicked/whatever else they do to it. 2- since the wad is placed inside the tube of TP, it acts as a barrier so the spider cannot escape the inner cushioned center. I've seen cases of shipped spiders that were able to escape the place of cushion and get trapped against the hard edge of the tube. Some were fine, some were crushed and died. It will look like this (see how comfy and soft this looks?!):
I like to make sure the tube has a little bit of moisture/humidity for the typical 3-day travel. You can either drip water down the sides of the vial/tube and bottom, or you can use a syringe and do the same:
Now that your cushioned tube is ready, get your spider and catch cup. Make sure you clear the area as you don't want your spider to get loose and then lost. I always make sure I have plenty of room to work with. I've had a spider make a run for it before when there were other unnecessary objects laying around. The web the spider was laying as it ran got caught on the object and when I went to remove the object the spider came hurtling along with it, right onto my foot. Lesson learned. Now, remove spider from its enclosure. Stick comes in handy here.
Many times the spider will run right into the tube if you do it right:
Other times, she might need a little help :) This is the second time where the stick comes in handy:
Okay, safe inside, tucked away:
I always have a little clear piece of plexiglass nearby for when needed. It can come in handy if you need to put a lid on the spider while you do stuff or need a break or whatever. You never know when it will come in handy. It is better than using the lid because you can easily keep track of the spider:
Wad up another small piece of TP (this will serve the very same purpose as the one put at the bottom from earlier):
Shove it in the top (hence why you left a little bit of room earlier! Aren't you glad you did that now?!). It should look nice and neat like this:
Put the lid on. Make sure it is secure! If it is not a screw-on type lid like the one shown, I like to secure it with a little piece of tape, just as an added precaution.
Label your vials with the appropriate information to eliminate confusion. Typically I will put the scientific name and sex on the sticker or vial. If sending unique spiders, label those too. Help your buddy on the receiving end out! As an added tidbit: it is usually acceptable to abbreviate the genus name, while spelling out the species name. And if you see numbers like this: 1.2.3 they correspond as such: male.female.unsexed. So as you can see here, this is a female L. hesperus:
Once everything is packed and labeled, get all your shipping supplies ready. You can use anything really, but I prefer to use any of the following for padding: bubble wrap, newspaper, peanuts. I've found newspaper to be the best and easiest though. Free, sturdy, not messy. A cooler for insulation (as shown) is extremely helpful for shipping in either really hot or really cold weather. The spiders are extremely hardy critters though and can survive almost any swing of temps. Use a good box as they get smashed quite easily.
(For this example) take your tube and roll it up in bubble wrap:
Place it in the box in such a manner that it won't get jostled around too much. We will secure it further in the next step too though.
Pack newspaper (not too loosely, but don't absolutely cram it super tight either) around your tube so that the contents won't get moved around a lot during transport. By packing it like this too, it will make the box more solid should it get crushed, and will provide a bit more insulation as well.
Once everything is in place and feels good, put the lid on:
Tape the box up, make sure nothing will come apart or off during transit. Attach label and make sure everything is as it should be. Use whichever shipping company you like, just be sure to check the laws before doing so!
When it comes to shipping spiderlings, it is incredibly easy (except for the separation! but we'll talk about that...).
If you plan on shipping an entire sac-ful of slings to someone, do yourself a favor and put the eggsac in a shipping container so that when they hatch, you can just put them in a box and send them on their way. The beauty of shipping slings lies in the fact that since their bodies are so incredibly small, it is almost impossible to rupture their abdomens. The only thing they seemingly die from during shipping is dessication and/or starvation.
If you must separate slings after hatching, well, beware. I've done this several times and it really is an exercise in concentration and patience. As soon as you open the lid of their container they explode into 360 different directions at the same time. I end up using about 10 catch cups to catch strays. The easiest way to ship a small group of slings is to use the small dram vials (with white snap caps) with a small piece of TP in there for them to climb on. They will occupy the little niches in the folds of that small piece.
Always be careful as you unpack your shipment of widows. You never quite know how they've been packed and where the spider will be. Use tongs to remove any packing material and not your fingers. It is nice, however, to say 'ello to your widows when they arrive. Shake their leg and welcome them!