This is an online tool for you to upload a file to 3D print. It adds temperatures gcode commands according to a special fractal "noise", in order to create horizontal stripes that "look like wood" (like the background image).
The effect is mostly visible with filaments like laywoo, woodfill and a few others, when they embed fine particles of wood that darken with higher temperatures (well, some of them behave in the opposite way).
The underlying engine is a Python script which I originally described on
my blog
(source on github, or via my thingiverse account).
Trivia: the early prints were featured on Wired
back in 2012!