What technological challenges stand in the way of making molecular assemblers? I mean, what exactly would it entail to generate some sort of nanotechnology that could assemble, from scratch, a car or something? I've heard something about the "fat fingers" and "sticky fingers" problem and something about a debate between Eric Drexler and a professor name Smalley. I'm just wondering if it's possible that we'll, one day, have molecular assemblers. Any thoughts?