And besides what waltr mentioned, I would add...
Yes, the guy who made it has... Well, made it and so, it's doable, but he moved on to a better version.
You would do wise in using off the shelf components until you have the experience to decide for yourself what you are able to do, as nobody else have a chance of knowing your skill- and experience level.
If I was to make something like that, I'd first consider how many degrees I wanted it to cover (in integer parts of 360°) and then make an über balanced polygon mirror on a fast rotating spindle (the faster the better).
Some of the large and fast photo copiers have got a polygon mirror integrated with a motor going around 40,000 RPM, and that would be a nice unit to build on.
For best effect, you need prisms as well, as both in- and out going LASER beam needs to be coaxial, so you need to be fluent in optics as well as electronics and fine mechanics to pull this off.
The thing is that you probably don't need it. A Sharp sensor will tell you when you need to act - if you build a sensor that finds obstacles 50 meters out, you're far to far away to act upon it anyway, at least until you build a 'bot that covers that distance in between 10 and 50 instructions time, which on a slow 1MIPS controller will be around... Never.
If you wanna build it for the fun of it and for getting your own construction experience, go nuts, but if you want stable navigation, go with the Sharp or similar.