I want to know the answer to the following question:
Pressure is one thing you need to apply to make a multi-layer PCB; what's the other thing?
All the background I'm provided with is that "For example, a four-layer PCB can be fabricated by starting from a two-sided copper-clad laminate, etch the circuitry on both sides, then laminate to the top and bottom pre-preg and copper foil.". Is that enough to answer the question?
Answer: no