Comment 3 for bug 1672149

More people are clearly looking for this:

https://www.reddit.com/r/Machinists/comments/3f6n9f/tool_for_measuring_total_path_length_estimating/?st=j06pxs5q&sh=bfaf56b8

Similar functionality is hidden in Adobe CC:
http://graphicdesign.stackexchange.com/questions/65232/measure-path-length-in-illustrator-cc

https://github.com/fablabnbg/inkscape-centerline-trace might have some relevant functionality on board. (Grep the README for "length".)

http://dangerousprototypes.com/blog/2016/05/31/how-to-measure-laser-cut-length-or-time implements a full measure too...