The Noise Generator dialog allows you to quickly create flat tiles from a randomly generated noise texture (using the OpenSimplex noise function). It can be accessed from the Voxel Editor toolbar when editing a tile. To use the tool, select a base color from the color picker button, then click the “Generate” button until a desired pattern is achieved.
Once you are happy with the generated texture, click the OK button to apply it to the bottom voxel layer of the current model frame. Shown below is a preview of the tiles created from the noise texture that was generated in the dialog window above.