This is a tetra-pod made mainly out of carbon atoms in tetrahedral sp3-hybridization.
As a peculiar oddity here the part has the same symmetry as the atoms it is made of.

The surfaces are passivated (bonds plugged up) mainly with Hydrogen (white)
to make the surfaces chemically non-reactive.

Some sorts of productive nano-systems like nano-factories 
will be needed to produce / "print" objects like this.

Terminology

DMSE … “Diamondoid Molecular Structural Element”
-- very stiff and crystalline 
-- very small 
-- non active non moving 
-- building block

This acronym is rather unsuitable for use in natural language so I'd like to advertise the portmanteau:"crystolecule" for building blocks of this kind. It seems fitting since they are small like molecules but their interior has a dense three-dimensional polycyclically meshed and ordered structure like a crystal.

Details

This structural crystolecule is meant to be used in bigger frameworks like nano-housings etc. The strut ends are unsaturated “surface-interfaces” for “seamless covalent welding”.

The seven open bonds can be put together in two different ways with the seven open bonds of another tetrapod.

Thus when assembling the tetrapods beside "normal" cubic diamond structure also hexagonal lonsdaleit structure is possible.

You can find more technical information about mechanosynthesis and atomically precise manufacturing in general on my website: http://apm.bplaced.net/ 
or in the book "Nanosystems" written by Eric Drexler. 

Related

Somewhat related to this is one of the simplest possible structurally usable 2D fractals: http://www.thingiverse.com/thing:14023 .
Extruded this would form some spongy hexagonal tube structure.

Instructions (may be quite outdated)

To create & convert such models for 3D printing:
You'll need: *) Nanoengineer-1 (http://www.nanoengineer-1.com/content/)

Alternative Sources: 
http://sourceforge.net/projects/moleculardynami/files/NanoEngineer/ http://diyhpl.us/~bryan/irc/nanoengineer/snapshots/*) Blender(2.49b!!) & Plugin: http://www.malte-reimold.de/blender/pdb2blend.html
Create something in Nanoengineer-1 &export it as .pdb

EITHER
Load the pdb2blend script directly from the creators site http://www.malte-reimold.de/blender/pdb2blend.html

Credit goes to Malte Reimold!

OR (RECOMMENDED)
Use the version that I've slightly modified (included below)
-) brighter atom colors - suitable for 3d printing
-) changed atom radii a bit
-) rectified the double-tabs to single-tabs on line 633 & line 700
[ still not working for newer blender versions :( ] http://blenderartists.org/forum/showthread.php?233937-TabError-pdb2blend

OR edit it yourself
) Right click on "pdb2blend12.blend" and click on "open with" -> "blender.app (2.49b)" (mac)) Right click on python script -> choose "Execute Script" from the context-menue

For maximal success rate use following settings:
Select: Balls
Atom Scale: 2.04
Atom Sum: 0
Atom Refinement: 10 (!!)
Stick thickness: 0 (irrelevant)
Stick refinement: 4 (irrelevant)

Low atom refinement means low probability of co-linear model edges (baaaad in*.stl's)
A hunk of non-shaded Atoms will appear.*) right click on the hunk ) Select all: Apple+A (possibly twice, why?)) Join Atoms: Ctrl+J ) export as .wrl /.x3d / .stl

*) print with printing service in color or on home printer in monochrome

It would be great to remove the useless internal structures without loosing the color information. Does someone know how to do this?

Category: Other
 

Reqired citations

Title picture made with:
QuteMolX, v.0.5.1, Nanorex, Inc., www.nanorex.com, 2010. http://qutemol.sourceforge.net/
Structure generated with:
NanoEngineer-1, Nanorex, Inc., www.nanorex.com, 2010.

And the paper that presented QuteMol:
Marco Tarini, Paolo Cignoni, Claudio Montani: Ambient Occlusion and Edge Cueing for Enhancing Real Time Molecular Visualization, IEEE Transactions on Visualization and Computer Graphics, Volume 12, Issue 5, Pages 1237-1244, 2006, ISSN: 1077-2626

All gone:
Model on Shapeways:
– six membered tetrapod ring
– single tetrapod
– Quick: http://www.shapeways.com/model/386826/