FreeCAD Stair Designer

Here is a video on how to design stairs in FreeCAD.

There are plenty of architecture stair designers in FreeCAD, from Arch workbench to macros. Parts of these can be used for the Seed Eco-Home 2 detailing:

1. Use https://wiki.freecadweb.org/Arch_Stairs to generate stringers - by creating a solid stair and flattening it to a stringer.