Interesting topic! May i ask for what you need this? And how about this, in case you have a flatbed scanner and the curves are planar. Cut a parcel twine to the desired length, scan it, deform it, repeat etc. and then redraw in MoI...
No math required. Maybe rigging in an Animation Software should work also.

Regards
Stefan

Hi Tom, no there really isn't any way to keep a bendy curve at a specific length while you move its control points around.

However, you could use the Transform > Deform > Flow command to map a line onto that bendy curve and the mapped line (as long as you don't enable the "Stretch" option in Flow) will have the same length as the original line. Maybe that method could help you.

- Michael

<Interesting topic! May i ask for what you need this?>

Thank you for the tip
Well i am working on a desogn where I need variations of a part
which should have the same length just think of a a bundel of wires of teh same length
which should be bent into different shapes

Hi Michael, thx for the tip !

So others have tried the same before me ;-)