To make a liter or so of chicken stock:
2-3 pounds chicken parts (1 pound feet, the remainder legs or thighs) go into a pot with 4 liters water. Bring to a boil and reduce to a simmer, skimming off scum til mostly clear (20 minutes) and until liquid volume has reduced by a liter (in my wok, til the liquid volume drops from the top of the handle rivets to the bottom.)
Add a bunch of green onions. Cover. Slowly simmer until chicken is extracted and falling apart and green onions are limp and colorless (2 hours).
Strain. You will have around 2 liters of usable light stock; simmer stock with the lid off to concentrate down to desired consistency (for me, around 25% reduction over about 15 minutes). Aim for 1.5l stock.
Stock can be made straight into a soup, or cooled to room temperature and frozen.