@Jules showed me how to do what is called a “knockout” in cartography, blocking data in one layer using data in another layer, using Inkscape. I usually use GIS software for this and also for clipping data but was having a great deal of difficulty doing this in Inkscape. 
Following / experimenting / expanding on her advice, I can now do “clips” using multiple layers and Path>Difference. Originally, I could only get Path>Difference to give me ‘double lines’ once two layers were differenced. By using filled polygons but with no Stroke (as Jules had recommended when doing a knockout), I can now produce single line vectors during this differencing process. No need to select and delete nodes to make single lines from double lines!
Yea and Cool!
I could do this in Fusion 360, but Inkscape is much easier to use for me.
I suspect many people already knew this, but this is exciting for me and will make my work easier and faster!!!
Of course, the downside to all this is that I will have to replace my GlowForge tube a lot sooner because I will be able to pump more work thru the GF! 
Thanks Jules!!!
