After seeing a few pictures of this online, I decided to try it myself. I usually use the traditional plastic cell-packs in a seed-starting greenhouse (see here on seed starting). However, I am always looking for ways to get away from using plastic as much as possible in all aspects of my life, including gardening. Also, it's always my goal to have as few inputs as possible into our gardening efforts, closing the loop as much as is feasible. One way I might be able to close that loop a little more is through using our empty toilet paper rolls as seed-starting pods instead of ever investing in plastic cell packs again... and the best part is, they're biodegradable! I can just plant the whole pot, and let them break down in the soil. See tutorial below on how to make your own.
Start with a clean, empty TP roll.
From here, shmush the roll down to fold it in half so that it has creases running down the sides. The unfold and shmush it down so that the existing creases meet in the middle. When your done, it should have taken on a square shape like the picture below.
If you want more defined folds and to save your hands a little effort, you can also use a ruler on a hard surface to give the roll a hard crease.
Now, you want to cut up the creases on the bottom of the roll just enough to make flaps that reach halfway across the opening of the roll. All rolls are a slightly different size, so I am not bothering to give an exact measurement. For example, the fluffy stuff Derek had here originally had much wider rolls than the Seventh-Generation I replaced it with... kudos to Seventh Generation for giving us less empty space.
Fold the flaps so that they are creased across right where the slits end (like pictures below).
Finally, fold the flaps as you would if you were trying to close a cardboard box by interlocking the flaps, as pictured below.
You can make a whole bunch in just a short time!
And they'll stand up to fit in your seed-starting trays right along with those old cell packs... And then when your plants are ready to go outside, you can bury the whole things in the ground, and it will break down on its own.
~*NOTE: I have not yet planted these, so I'll let you know what the positives/drawbacks are once I know. However, similar to peat pellets, I would recommend that you be sure to bury the lip of the roll completely under the soil line, or else it could act as a wick, drying out the roll-pot, and thus, your plants. *~