Hi, I am wondering if there is a way to take a line with a stroke and no fill, and to make it into two outside lines, with a fill. it would look the same, but would be very different when it came to things like vinyl cutters, Thanks!

Hi.

You can convert strokes to paths by Ctrl+Alt+C.
May need editing miters and displaying it in outline mode (Ctrl+5 on the numpad to change display).
As "would look the same" doesn't always stand, if the original path was compound and had a hole inside.

Check your other topic.

For such purpose in general I'd recommend lowering the opacity to 50% and adding a black fill,
so that if you break apart a compound path (Ctrl+Shift+K) you can have a better sence of the objects.
If a closed path's stroke is converted to a path it has to be compound. See the basics of such holes.
Keep an eye to the z-ordering of the objects, the larger subpath can be on top on the smaller one!
Can use outline display mode or Alt+Click for selecting, and/or use the Home/PgUP/PgDown/End keys.

Other than that you need boolean operations and editing nodes.
Which doesn't work between groups and clones as per se in your attachment, you need to get rid of them first.

Thank you so much, this saved me so much time and effort trying to redraw things, Thank You!

Another fantastic mind-reading job, Lazur!

My best guess would have been Stroke to Path, but I would ask for an example, to be sure.