Installation

In Blender open Edit, Preferences, Get Extensions, then use Install from Disk and pick the staircase_generator zip.

Usage

1. Open the Staircase tab in the 3D viewport sidebar (N). With no staircase selected, click the picture to choose one of the 48 designs and add it at the 3D cursor. You can also use Shift+A, Mesh, Staircase.
2. Select a staircase to edit it. Surprise makes a new random staircase, Vary changes the current one a little, Random Finish picks a new set of materials and Reset returns to the design.
3. The tabs hold every setting: Layout (plan, height, risers, going, width, turns), Steps (treads, nosing, risers, starter step, carpet, lights), Structure (stringers, concrete, floating, suspended, wall), Railing (style, balusters, handrail, newels), Finish (materials and colors) and Export (detail, bevel, Convert to Mesh, Delete).
4. Click the picture next to a setting to see all its options in a gallery, or step through them with the arrows.