I think these things are getting close to technically feasible today, but I don't think (in spite of the existence of the Foresight Grand Prize) anybody in a position to do it is looking at it as an important goal to pursue. A few possible obstacles occur to me off the top of my head.
- Maybe the amount (US$250000) is just not enough to attract the requisite talent.
- Maybe the people able to do this are busy with other things, and consider this a pointless diversion from more important goals.
- Maybe there just hasn't been enough publicity for the Grand Prize to be well enough known.
All these could be addressed by growing the amount every year. The money could be put into an index fund, and Foresight could solicit yearly donations from well-heeled donors (and pittances from us in the peanut gallery).
The prize does state size limits (100 nm cube for the arm, 50 nm cube for the adder) and I haven't thought hard about whether these are close to what could be accomplished with, say, a reasonable DNA origami design. It would be good to take a few steps toward the prize by first doing some back-of-the-envelope feasibility calculations like that, and then if that looks good, starting to propose structures in broad strokes. There is an impressive-looking open source CAD package for 3D origami available.
== Resistance is futile. Capacitance is efficacious. ==