Growing a shape in one direction I have this complex shape.



I need to grow the bottom face downward such that the top geometry stays the same, and all the edges along the sides maintain the same vectors that they have right now. (In addition, the top needs to also remain exactly where it is.)

Put in other terms, picture a pyramid. Then chop off the top and remove the base. I have the top of the pyramid and need to create the base again.



I need to create the base (highlighted) and place it in the exact correct spot).

Anyone know how to do this simply? If I could figure how to grow (only one side) an edge along its vector that would work great. Or simply transform the vertices along that same vector.
You can slide edge loops by double tapping  G. Then use Alt or C to make a loop go beyond the edge limits.

You can find more options here under "Edge Slide"
https://www.blender.org/manual/modeling/meshes/editing/edges.html