To make a liter or so of chicken stock:
2-3 pounds chicken parts (feet, and legs or thighs) go into a pot with 4 liters water. Bring to a boil, skimming off scum til mostly clear (20 minutes or so) until reduced by a liter (in my wok, til the liquid volume is just under the handle rivets).
Add a bunch of green onions. Simmer covered as low as you can until chicken is extracted and falling apart and green onions are limp and colorless (90 minutes - 2 hours).
Strain. You will have around 2 liters of usable light stock; concentrate further with the lid off if desired. Over-extracting bones can lead to a bitter stock; aim for 1.5l stock.
Stock can be cooled and frozen from here, or made straight into a soup.