Metro can use two kinds of seed stages. Traditionally, Metro has used a stage3 as a seed stage. This stage3 is then used to build a new stage1, which in turn is used to build a new stage2, and then a new stage3. This is generally the most reliable way to build Gentoo Linux or Funtoo Linux, so it's the recommended approach.
After switching metro builds to Funtoo profile, Gentoo stages are no longer provided!