From FreeCAD Documentation
- Switch to the Curves workbench (install from Addon Manager is necessary, if not previously installed).
- Optionally select vertexes, edges and/or faces:
- The number of vertexes of the spline will match the number of selected elements.
- The spline vertexes will be snapped to the selected vertexes, and to the midpoints of the selected edges and faces.
- To invoke the command, do one of the following:
- Press the button in the Curves toolbar.
- Use the Curves → Freehand BSpline entry in the dropdown menu.