Michael, thank you so much for taking the time to explain that to me. I would not have thought to model like that had you not.

However, one step I do not understand though is where you Construct / Offset / Shell and then use Construct / Boolean / Difference to give the model volume. I don't get how you've done this? The offest seems brilliant but it doesn't 'close' the model or give you the option to? Also using Boolean Difference I don't see how you've managed to close the object?

I hope you can spare me some more time to fill in these last parts of the puzzle for me!

EDIT! Hold everything, just seen the 'Shell' submenu in Offset! What an idiot.

Anyway thats sorted now. I've got my shell looking great with thickness and a fillet. Now I've sweeped a circle along the shells outside curve and then attempted to Boolean/Union the 2 objects. Unfortunately it doesn't work? I've applied ajoin to both object but it hasn't made any difference. Furthermore I can't seem to 'jion' the sweeped circle? It only stays in 2 halves?ve attached the current file.