Thanks, that works great. I'd like to hear more about the plugins for simplifying the tedious manual work... I'm already using weld.rb and simplify_contours.rb

I'm new to sketchup, but not to 3D modeling. I'm creating some rather complex terrain using Sandbox From Contours. I've been creating it in sections, assuming I can stitch the different terrain surfaces together for smoothing as long as they share edges, but can't figure out how.

Is there a way to weld vertices, or to draw a polygon between two objects in such a way that they become joined?