Building Block: Truncated Octahedron

## A simple Construction brick.

**derived from this more general tool:**
http://www.thingiverse.com/thing:409443

Multiple of these bricks can be connected with short pieces of ~3mm diameter filament.
Tip: If the bricks doesn't go well together the first time they are assembled a mini screw clamp can be helpful.
This brick has 14 faces to it's nearest neighbors.
(six cube faces and eight octahedral faces)
### Background:
This brick is the Wiegner-Seiz cell
http://en.wikipedia.org/wiki/Wigner%E2%80%93Seitz_cell
of the body-centered cubic crystal system
http://en.wikipedia.org/wiki/Body-centered_cubic
.
The three main surface orientations (111) (110) (100) can be built without staircase effects.
Notation: http://en.wikipedia.org/wiki/Miller_index
(100) surfaces with squares up need a second layer to close the square holes.
(110) surfaces with edges between hexagons up are easiest to build.
(111) surfaces with hexagons up need two layers to be built an