LDraw is a free "CAD"-like set of programs that allows a user to create virtual LEGO-like models on your computer.

You can use it to document models you have physically built, create building instructions just like LEGO, render 3D photo realistic images of your virtual models and even make animations. The possibilities are endless. Unlike real LEGO bricks - where you are limited by the number of parts and colors - in LDraw nothing is impossible.

You have an unlimited supply of virtual bricks in every possible color. Even colors that LEGO has never created!