The complete set of symmetrical T-shaped #Stemfie3D beams. The 191 files, ranging from three to twenty block units (holes), are available in STL and stepZ format, which you can open and edit using FreeCAD (https://freecadweb.org).
Link for stepZ format: https://get.stemfie.org/Beams/Angled/T-shaped/Symmetric/CAD/