This is an outdated tutorial. If you are using a more recent version of grasshopper please watch this video instead - http://designreform.net/2011/03/rhino-grasshopper-parametric-truss-update
In this Grasshopper video, we will create a parametric truss system by generating and manipulating components and instantiating them onto a lofted geometry. We will start by creating our components from a surface using such features as List Items and Offset. From there, we will continue by subdividing a lofted geometry and then instantiate our parametric components across that surface, creating a parameterized truss system.