A wall is then developed around the brackets. Then the finished treads are bolted in position. These treads can be of metal or Wooden or wood clad steel. Cantilever ways should be built by a structural engineer, so that they continue to be horizontal and rigid with use over time. https://staircaseinspirations.weebly.com/blog/the-rise-of-cantilever-staircases-in-contemporary-homes