Yup, like @Randy Abercrombie said, a PVC irrigation pipe. You should get the largest size they have with a threaded end, so you can get a cap they can screw on and still remove. Cut to the size you want and seal the other end with a glued on cap.
Please don't take this the wrong way, I'm just curious, do you torture small animals in your spare time?
Thank you! Any advice on the kind of glue to use? (I'm female and don't spend much time in hardware stores.)
The hardware store in my area is a national chain, and the people who work there are not helpful. Remember that Radio Shack (RIP) commercial "You've got questions, we've got answers"? Well, they don't have answers in that national chain hardware store, ever. They would point me to where they sell glue and say "Uh, any glue will work" but then when I get home, it won't work. So, I don't rely on them for any help. No matter how many times I've asked, they always come up short.
There is a specific glue to use on PVC. But, you are right about help. Google it and see what you need before you go. Read up a little. There will probably be pictures included. Even a U Tube video might help.
Great idea! Thank you! I know it sounds strange, but I keep forgetting that I can ask Google these kinds of questions. For most of my life, and certainly most of my adult life, I lived without Google. I have to "remind myself" that it's a place that has information. It's a strange thing, but, old habits die hard.
Since you're looking for something that won't deteriorate over time, maybe they should tuck them inside a McDonald's hamburger. Or a Twinkie.
The plastic containers won't leach anything that the vegetables would pick up. This from an environmental chemist.
If plastic can leach into water, and vegetables planted nearby are using that water to grow, how can it be that there is no leaching into the vegetables? I'm not trying to challenge you, I'm just trying to understand.
It would be cool, but as TheFinn said, it's full of Chinese toxic waste. I wouldn't want that buried anywhere near a neighborhood inhabited by human beings.