Freecad
From Wiki2
tricks and tips
tripod
background:
draft on 2 planes then connect them with a sweep (CADZiS) rotating of shapes is tricky my example in onedrive/cad/trangleConstrained2rotate
https://wiki.freecadweb.org/images/1/10/PartDesign_Body.svg
offset rectangle
https://www.youtube.com/watch?v=pdm-GUvisJo
https://www.glassondesignstudio.com.au/blog/how-model-mortice-and-tenon-joint-using-freecad
I was finally able to get an offset rectangle with this sequence:
Select rectangle.
Click on Offset button on toolbar.
Click on Copy button in Offset dialog.
Move cursor to inside/outside of rectangle in main window.
https://wiki.freecadweb.org/images/f/fa/PartDesign_LinearPattern.svg
Enter offset into Distance edit box in Offset dialog.
Strike Enter.
Jul 28, 2016
How do I make Draft Offset work? - FreeCAD Forum