TL;DR: remove bottom and cap and tower them; compost done in any way possible Show more
well, maybe couple of things aren't clear from the pictures.
Basically you cut the bottom of the bottle and remove the cap, you fill the bottle with soil and you tower them. They are individually tied so they don't put much compression on the one underneath.
The soil of each one is touching the one underneath (the bottom one is in the soil), so that water is allowed to get down.
On the side holes were cut to put the seeds and plants in.
If you are really interested in it, once I have the technique right next time I do it I can take pictures of the process, maybe even make a video (I feel I'm too lazy for that, but I can try) =)
Well the composting is a whole different story, I have couple of worm composting bins, a small garden with a composting hole, and a compost tumbler. Once the compost is done, there are no scraps anymore, only rich dark soil =D
@DecaturNature If there is anything I can explain further just let me know, I'm more than happy to share