Extrude a curve perpendicularly at a random distance

Hi everyone, I'm trying to perpendicularly extrude a set of curves a random distance.

I've managed to extract points that are perpendicular to their original lines but I'm struggling with the extrusion part of it. It's all 2D in the XY dimension.

See the attached script, model, and image for my best shot at this.

Of course I'd appreciate any help. I feel like is a pretty simple problem so I'm frustrated with myself for not being able to get it!

Thanks in advance for any help,

Ian