Hi Gord,
If you want to 3D print that model "as is" I would say just select everything and export it as STL.
I found this workaround OK as long as you won't split your object in slicer program.
I've had hard time combining complex objects and if I export everything selected, slicer program accepts it as one object.
I use slic3r PE and it works fine.
However I recommend to check layer preview before hitting print.

Juraj

I have gone over everything again and it is now joined up. I have saved as .STL and am sending a test piece off to the print company for their comments.

Thanks!

Gordon

Just a thought
You can try not joining your parts and export the stl file with all of the components , I find that if they are touching or intersecting each other it should print.
I find unioning parts sometimes generates errors
Also Un unioned models are easy to change later if there any problem parts
cheers
shayne