Creating a border.

Hi all,

I started using grasshopper a little while ago and its great, I was still able to figure stuff out on my own but now I've got myself into big troubles!

In short what i want to do is this, I want to create a free-form curve in rhino that will function as a border. This curve will then represent the outlines of a construction-site. Within this border i want to create a structure. Creating the outlines of the construction-site is not a problem, after i made the curves i divided the curves in loads of points so that i would receive accurate data from it. The question now is how can i use these points as a border/maximum? Because i want to use it in a way that if i create a box/plane within the curve and this object is growing it will not be able to exceed the curve but will expand in an opposite direction where there is room.

I hope its clear and that someone is able to help me a bit!

Greetings,

Kevin.