One of the materials now available in 3D printing is wood filament, designed to mimic the look and features of natural wood. It is a composite material that typically is mainly polymer (60-70%) and containing a lesser amount of wood fiber (30-40%). Most of the available options seem to use PLA as the main binding polymer, but with a variety options available for wood fiber to produce different properties and qualities. Wood fiber types seen in use include basics like pinewood, bamboo, cork, coconut fiber, and purportedly higher quality woods such as oak, mahogany, and ebony.
Due to wood’s nature, filaments containing wood fibers can be very sensitive to temperature, and can be made to become darker by increasing the extruding temperature. If scripted, the effect could be embraced to add a visible layering feature that can appear much like the grain in natural wood, and may be enhanced with wood stains. Additionally unlike pure PLA prints, wood filament prints are more easily sanded.
To avoid clogs, a 0.4mm or larger nozzle is recommended, some have reported that 0.5-0.6mm nozzles have been more reliable for avoiding this. Wood filaments are reported to work better at higher layer heights, and while it is recommended to avoid keeping the material heated to long in the extruder it is also important not to increase the too high or it may not reach the needed temperature for a successful print – 50-60mm/s (and up to 80 mm/s) is the print speed range I’ve seen used.
References:
How to print with woodFill filament
Shades of brown with wood filament, via varying temperature
3D Printing Wood and Sweet Finishing Techniques
Woodworking with a 3D Printer – PrimaSelect WOOD review