Make a model from ordinary hard cardboard.

For the manufacture of three identical parts of the structure of the stairs, you should prepare a special sample, a bowstring model. Make a model from ordinary hard cardboard. Initially, measurements are made and all the necessary sizes are calculated, then they are applied to the cardboard. The finished model must be carefully cut. With the help of a cut template, three identical bowstones are made. Subsequently, the required number of steps is set on these a bowstring.