Hi, 
I am drawing a few letters in Inkscape cause I need them for a project, I am using Lightburn and a 3D Printer with a pen attached to it. And I want only the centerline of my drawing because i only need one line on my paper sheet. 
Can I edit my previously done Letters or do I have to make new ones?

If not how can I create new ones with just a centerline?

Thanks

(I am using Inkscape not very often, so there might be an obvious solution to this but I cannot find one)