3D printing on Atomic Level

[mechadense]

To place atoms you don't have to handle subatomic particles like protons and electrons.
It's as good as prooven that 3D Printing on the atomic level is possible.
Single atom manipulation at room temperature has been repeatedly demonstrated with AFM & STM microscopes (ultrasharp needles)

Atomically precise 3D printing is being actively researched.

The most intensively studied method is to use whole welding gas molecules (HCCH) as resource material.
Here is an attempt to design a closed cycle or tools that can be charged and discharged with defined molecule fragments.
http://www.molecularassembler.com/Papers/MinToolset.pdf

To do atomically precise (AP) 3D printing at roomtemperature you need stiff nondiffusing suff or else everything you place will wobble and jumble away.
Nonmetal crystals are stiff and nonndiffusing - so they are producable by that method (not food or other stuff thats soft in the nanocosmos).
Nonmetal crystals are brittle but when nanostructured arbitrary material properties could be emulated.
Source: "Nanosystems" by Eric Drexler
Here are some functional elements that today everyone can simulate but noone can built:
http://www.imm.org/research/parts/
The stiff structures allowes crude emulations (force field - not exact QM) to be quite correct.

What we have today is a chicken egg problem. You need an atomically precise 3D printer to build an atomically precise 3D printer.
Well not exactly but almost.
We'll get there by iteratively improving our tools and closing the gap between top down technology MEMS (= micro electro mechanical systems)
and bottom up technology like (Structural 3D DNA nanotechnology) shown here:
http://wyss.harvard.edu/viewpressrelease/101/
(The rather soft flexing structures are ok here since you need only placing accuracy of one block not one atom.)

What we need to do is to find ways to get the positional assembly capabilities of MEMS (aka robot arms) into systems of those atomically precise nanoblocks.
So that they can be used economically and then go futher steps to stiffer and stronger materials
like in a first step to silica & pyrite in water and in a second finally to mentioned nonmetal crystals silicon and diamond in nancapsules of perfect vacuum.
Source "Radical Abundance" by Eric Drexler

more diamondoid machine elements:
http://www.somewhereville.com/?page_id=10
http://wiki.transhumani.com/index.ph...ular_Machinery