Vincent,

Indeed, I used v3.0 beta 14, but the sh3d file is compatible with v2.6: I didn't use any of the new features in this model. The beta version does not support some of the plug-ins .

If you open the sh3d file, you can see I used 4 triangles. The dimensions of the triangles determine the beveled edge and the height of the window.

After creating the model, I exported it as OBJ file and then re-imported it as a door/window. All pretty basic stuff which you can read here, here and here.

Hans