It is easy to make a decompostable seedling pots for growing plants from seeds. A lot of the vegetables plants such as Tomatoes, Cucumber, Chilli and other vegetable plants doesn't like their roots to be disturbed during transplantation from indoor to outdoor. Most of the pots sold in the market involves some kind of pulling out the soil along with the roots from the seedlings plastic pots and then replanting them into your garden during the warmer weather. The problem with this kind of method is that the roots are disturbed while you are transplanting them by pulling out the soil along with their roots and then replanting into the garden. The plants would suffer what you can call it as "Transplant Shock".
So the best way to transplant a plant is to let it grow in a decompostable pots and then when it is time to transplant them into outdoors, you simply bury the pots into the garden soil. The pots decomposes in a few weeks and turns into soil allowing the plant roots to flourish and spread deep into your garden soil. However keep in mind that you should allow your seedlings to stay outdoors in the decompostable pots for at least two weeks for the seedlings to harden and get used to the outdoor weather and sun. Do not put the young seedlings under the midday sun, always let the seedlings get the evening weaker sun. Keep it away from windy areas too as too much wind can make your seedlings bend too far causing breakage at the root stem level. I once made a mistake of directly planting my seedlings from indoor to outdoor and the seedlings sure enough died in two days. All my efforts of keeping the seedlings alive indoors was wasted away once i put it outdoors. So don't repeat the same mistake that i did.
To make a small decompostable pots you need to do the following:
(1) Use the middle portion of a toilet paper roll as a decompostable pots vertical base. (After you finished using up your toilet roll).

(2) Then you cut some food fresh wrap and wrap it underneath the toilet roll vertical base.
(3) Tie a rubber band over the side near the base of the toilet roll to keep the food wrap from slipping out of the vertical toilet roll.
(4) Fill the inside of the toilet roll with seedling starter potting soil.
(5) Plant your seeds inside the soil.
(6) When the seedlings is ready to be transplanted out and after hardening off the seedlings (Keeping it outdoors for at least two weeks), you can then remove the rubber band and the plastic food wrap, and plant the complete toilet paper roll base into the soil without disturbing the roots of the seedlings.