These are good for storing just about anything small you don’t want crushed, spilled, or dampened: Batteries, earbud headphones, mini-first aid kit, medicine. They can also be used to carry liquids on a plane, as they hold about an ounce under TSA’s 3-ounce limit. I’m currently using one (pictured) as a throw-in-my-bag mini-EDC kit, in case I don’t have room for the regular Every Day Carry bag.
The ones I liberated from my son’s Scientific Explorer kit are also sold individually as Tube Vaults by County Comm, but the best deal I’ve found is 15 for $10 from Steve Spangler Science. According to their site, the Baby Soda Bottles are actually our ubiquitous 2-liter soda bottles before they’ve been heated and stretched, which explains why the caps are interchangeable with soda bottle caps.
The County Comm site shows video of a truck driving over one, so they are obviously sturdy. While there’s a more expensive version with a special cap for threading a carabiner through, I doubt it’s worth the extra money.
These food-grade polyethylene test tubes are dishwasher safe, strong, waterproof and, yes, I’ve used one to hide a geocache!
— Mike Everett-Lane
Available from Steve Spangler Science