Draw a line in a CAD program. The line will have a starting point, a direction and an ending point. Make a box. The four sides touch and the end of one is the start of the next with 90 degree turns at each endpoint.

Now take that profile mentioned in Laser Scanning and think of it as hundreds of tiny lines connected together. Imagine the lines are so short they aren't even noticeable. Each start and end point has a unique position, like a square on a piece of graph paper, and the computer gives each point an x, y coordinate.

If you hooked an electric motor to each knob of an Etch-A-Sketch toy, the computer could turn the knobs and connect all the x, y coordinates to recreate the line exactly. What's more, since each point is a number that can be multiplied or divided easily, the Etch-A-Sketch can recreate the profile in virtually any scale. You can even tell the computer how big your Etch-A-Sketch window is and it will break a 500-ft tall profile into pieces small enough to fit the window.

Now, forget the Etch-A-Sketch. Hook the electric motor up to a couple of screws that push a tool around, like an overhead crane in a factory which goes the length of the building with a beam across the width. Hook a router or cutting tool to this motor and instead of a little point drawing a line on an Etch-A-Sketch window you have a router cutting out a piece of wood, foam, aluminum, or granite -- the type of material depends on the machine and the cutter.

A CAD image can be scaled to any size and be cut out of a variety of materials. Generally, large-scale projects are cut from foam in slices which are then stacked, smoothed and used to create a mold. Smaller scale projects may be done with our 3D router, which can cut the whole shape out of a single block of foam.