The body centered tetragonal carbon lattice is a stable allotrope formed at extremely high pressures; only $12.95. If you try to compress it, you will see it is very strong like diamond & much stronger than graphite.
See Related Images below for different views of the model. There are no written instructions but the structure is simple to build.
The body centered tetragonal structure shown in the image is a recent discovery of another carbon allotrope. This model measures 100mm cube or ~1L in volume. This material may even occur naturally on an exo-planet, Cancri e, some 40 light years from Earth.
Click on this paper on Body Centered Tetragonal Carbon pubished in 2010.
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