One of the ways laptops are made is through a “subtractive” process. In this process, a circuit board with the desired shape is etched in a non-conductive material to form copper traces. Connecting joints are then cut from another metal sheet and contiguously bonded to the ends of the conductive tracing. This ends up being an inexpensive way for rapid prototyping because few materials need to be used and it can easily feed off its own waste product.
In subtractive processes, an excess amount of one or more substances is applied so that subsequent material removal will leave desired shapes behind, much like carving away excess marble from a block that creates a statue.