Wood is a curious material. You can see its history in a slice, due to its imperfect rings. I wanted to recreate a simplified version of this.
First, I created a skeleton of line segments to represent the trunk and branches. From these, I created a 3D distance map. If I plotted the contours of this distance map, then the slices would just look like perfect rings around the trunk and branches. Instead, I used some “colored” noise (generated from an inverse FFT), which has few small perturbations, and more long perturbations.
I added this noise to the distance map, took the contours, and here is the resulting wood: