I have this 3D belt, doing this twists and rises.

I need to have it's length as a dimension (it is later shown in Specific properties)

The thing when the belt is in 2D, it is easy to use this function:

It just adds all line lengths into one Length. But the fature does not work with 3D sketch lines.

I thought of using weldments (for belt crossection), but my belt designs change so fast, it will be frustrating to edit Weldments all the time.

So while making these belts in 3D shape, using 3D Sketch and Sweep proves sufficient, I don't know a way to get a length of belt from this method. Maybe anyone has solution for this!

Happy Christmas!