1) Heat 1 cup milk, not to boiling.
  2) Add 4 tablespoons vinegar.  Stir for a few minutes.
  3) Strain out curds.  Squeeze to remove as much liquid as possible.
  4) Form into a shape or press into a mold, let dry.

That's literally a recipe for paneer cheese. Tastes awesome fried and mixed into many Indian dishes.

There was a variation of this in a midcentury science book for a children that I'd check out from the library as a kid. It was used to demonstrate how to make your own 'plastic' action figures.