While there is a total of nine important steps, the first two steps of investment casting are critical to the quality of finished parts. The first is tooling and pattern making. A very high-quality tool is made that has a specified shape or geometry. While this tool requires a significant investment, it will last a long time and result in many parts. Wax is injected into the tool, creating a pattern or prototype of desired parts. The second step is pattern assembly. Rather than make one casting at a time, multiple patterns are mounted together on a sprue. Channels are created that allow molten alloys to be poured into all the patterns at once.