This can be made with milk jugs too, like here: Milk Jug Slow Drip Watering System.
You just need to make some holes in the bottle, unscrew the cover and bury the bottle with the holes in the ground,next to the plant. Don’t forget to leave the top exposed.
This can be done in pots too but in stead of a large bottle you will need to use small bottles.
Awesome tips.