I believe its the reason that injection molding plastics is so popular versus doing metal and wood. Wood and metal most of the time require a subtractive(sp?)

I believe its the reason that injection molding plastics is so popular versus doing metal and wood. Wood and metal most of the time require a subtractive(sp?) manufacturing process that requires a lot of raw material, assembly steps, and waste. Injection molding and 3D printing is additive that is automated and simplifies the process with minimal waste.