Level it

I'm on a new quest: to find the highest accuracy laser level I can. I have some top-secret leveling I want to do. How am I going to justify the purchase? Like all good top-secret programs, I'm going to buy it for an altogether different purpose: to install floor tiling. So I want it to do chalk lines as well. Of course, a hugely expensive precision laser level may not stoop so low as to do chalk lines on the ground, but if I can find one, it might be worth it.

Accuracy seems to be spec'ed at 100 feet. Ones costing MANY hundreds of dollars are accurate to 0.125 inches at 100 feet. That accuracy would probably do for me, although honestly I'd kill for 1/16".

Turns out that professionals use the CompuLevel made by Stanley Tools (New Britain, CT). It was designed by Dennis L. Vories, P.E. Of course, it's $1000. A less expensive method would be a water level - either Watrlevel, or just make one myself. They also (very honestly) list all their competitors.