I also looked for diverse self-watering systems designs. I tried diverse ones, based on ropes, pieces of fabrics, and plastic bottles, and have not found a very efficient one yet.

Rope-based system

Water flows slowly from the bottle to the soil through the rope, by capillarity. It works but does not waters the soil enough.

Fabric-based system

It is supposed to work almost the same way as the rope-based system, but does not seem to be as efficient - it may be a design issue. A new version made of a continuous piece of fabric - and not small ones tied up together - should be tried out.

Water-layer based system

I found this design on Youtube. It works well (as long as you do not don't forget to plug the bottle correctly). However, the soil was too soggy with this system.

Good neighbour system

After these failures, Rasa offered me to take care of the seedlings when I am away, and I am very grateful to her !