The solid beech staircase is my design, it was modeled in 3D with Inventor software. It is composed of a central stringer and it has 5 balanced steps, the finish is a special colorless varnish for stairs. The assembly is done by gluing with dowels.
As tools I used a circular saw, a handsaw and a drill.
Under the stairs
the shelves are made with 18mm thick birch planks painted white.