I recently discussed the various requirements/procedures/biases involved in shipping samples to a commercial lab. So what if you don't use a commercial carrier, but instead either bring the samples over yourself or arrange for a lab courier pickup?
Some of the packaging requirements are easier. You're not packaging stuff to travel across the country, kept to a certain temperature for several hours (or more), and with the expectation that the packages may be juggled/kicked/dropped. However, you still have to ensure the following:
Maybe you don't need elaborate stuffing/packaging procedures. But bottles that clink are bottles that break. Individual bubble bags are still required, and some organizations still require bubble wrap at the bottom and around the sides of coolers.
Keeping Samples Cold
The lab still has the same temperature requirements whether the samples come in the mail or otherwise. You can still use ice cubes in bags, (maybe) gel packs, or freeze water in bottles. However, you don't have to worry as much about stuff melting and leaking. In fact, I've worked with several people who just upend ice cubes into the cooler, creating a "beer cooler" effect.
Here's why I don't do the "beer cooler" thing: Sure, it keeps the samples nice and cold. And sure, it's easier not to bother with filling and sealing bags of ice. But as those cubes melt, your samples will be sitting directly in a water bath, and if that water gets near the samples you may damage the labels or make it impossible to determine if the samples leaked. Also, I think it's obnoxious to force the lab techs to rummage around in a cooler full of ice-cold water/partially melted ice cubes.
You or the courier may not care if a bubble bag breaks or if you've got a bunch of ice water slopping around the cooler. But you still need to prevent sample leakage. If you're going to be casual about ice cube containment, you'd better make damn sure you have ziplocks for your sample bags. Otherwise, the same options apply: bubble bag only, ziplock on inside of bubble bag, ziplock on outside of bubble bag.
Sealing the Cooler
I once thought that I didn't have to seal the cooler if I was just going to hand it to a lab representative. I was wrong.
Maybe in certain circumstances, it's ok, but it's safest to throw at least one wrap of tape (usually with the chain of custody (COC) seals in place as required) around the cooler just so it's secure physically and legally.
Addressing the Cooler
Finally, something that we can drop entirely! Whew.
We discussed this in the comments to the other post, but if you're shipping something in organic solvents, you need to be aware of federal sample volume/packaging requirements. Those requirements don't go away if you are acting as the carrier (or if the lab is). Incidentally, if you're working out of a vehicle and you're carrying your stuff around on public roads, you need to be aware of those volume requirements at all times, and not just when you're actually preparing to bring your samples to the lab.
Takeaway: even though using/acting as a courier is easier than shipping via a third party, it doesn't prevent you from running into a tangle of standard operating procedures.