Twisting/bending a curve from sheet material

Hi all,

I am currently working on a project that involves the manipulation of curves from a flat sheet of material to generate three dimensional structural forms. I am new to Grasshopper and trying to get to grips with everything at the moment.

I have generated a basic 3 point curve and applied an offset and loft to generate a flat surface. I am hoping to then pull one of the Z values to 'twist/bend' the curve. Much like the effect generated in the paper model below:

Currently, when I move the Z point on the curve, the end vertices also rotate with the curve meaning that I do not get a 'twisting' reaction. It is merely the curve rotated slightly:

A few things I thought of to solve this were 'locking' the end points of the curve to fix them to the xy plane so when I pull the Z point up it is reacting to the end lines rather than rotating about a point.  The other was whether I need to create a mesh on the object to subdivide the surface so when it pulls it will have more freedom in terms of movement. Also not sure if this is something I should be using Kangaroo for, although I would like to control the amount I raise/lower the Z values.

Any suggestions would be much appreciated.

Kind regards,

Paul