Help needed to convert sketches into 3D solid.

[Formulator]

I'm trying to fill my FreeCad sketches out into a 3D form but the method of how to do so is eluding me. I've been trying to use the loft functionality and can only get a partial fill result or else really wacky shapes. Please can anyone advise how to get this done?

With thanks

Images and FreeCad file attached.

OS: Windows 10
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.17.13541 (Git)
Build type: Release
Branch: releases/FreeCAD-0-17
Hash: 9948ee4f1570df9216862a79705afb367b2c6ffb
Python version: 2.7.14
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 7.2.0
Locale: English/UnitedKingdom (en_GB)

[Willem]

Hi, welcome to Freecad and the forum. You have to install the Curves workbench. You can install it via Tools - Addon manager.
Info about working with it is here https://forum.freecadweb.org/viewtopic.php?t=22675

[Formulator]

Thanks for the tip Willem, I installed the Curves workbench but couldn't work out how to use it.

In the end I found that by using multiple B-Spline curves, one for each 'quadrant' of the profile in my sketch it offered more selective control over sections of the edges. Then when using the Surface workbench I was able to plot the profile using the boundary edges in two pieces.