Engineers at Columbia University have 3D-printed a block of "digital wood", using a voxel technique that enables the creation of objects with rich internal textures.
The resin block is modelled on an olive wood sample, with its exact grain pattern replicated throughout.
Because of the grain and colour gradient involved, this kind of wood effect was previously outside of the capabilities of 3D printing, but the Columbia University team used nascent technologies to produce the design.

First, they used destructive tomographic imaging to photograph ultra-fine slices of the wood, cut to just 27 micro-metres (0.027 millimetres) in width by a CNC mill.
The stack of 230 images was then fed to a Stratasys J750 PolyJet printer, which is capable of printing various colours and materials using voxels.
Voxels are like pixels in 3D space – they are the smallest elements into which an object can be divided in the design process.
With voxel printing, designers can specify the qualities they want every point within a 3D space to have – the Columbia University team said that for the Stratasys J750, that's a possible 760 billion individual voxels.

The researchers – Fabian Stute, Joni Mici, Lewis Chamberlain and Hod Lipson – detailed their method in a paper published in the journal 3D Printing and Additive Manufacturing.
"The final printed object closely resembles the original wooden block both in its external appearance and in its internal colour pat...