A digitizer will get you points. You can use a touch probe that's connected to a cnc. The simplest ones just beep when they hit something and you write down the x,y,z coordinates. You don't even need a digitizer, just touch the cnc tip to the object and write down the x,y,z. Gets kind of old after 1 or 2 points though nevermind 1 million that a laser scanner can get you.
Laser scanners work on triangulation or time of flight. You can google search these. Nextengine provides one for around $2500 or you can go to david-laserscanner for a free one (get what you pay for as usual). Nextengine has pretty good support online that you can chat with people.
Once you get the 3d points, a program like Rapidform (www.rapidform.com) will convert your 3d points to a CAD model (but you need to learn how to use it).
If you need more details, there's a lot of free information available on the web. If you don't have time to research everything, we can provide consulting services for a fee to answer all your questions.
Send me a PM if interested.