Voro is a GiD-plugin that wraps the voro++ open source program to create Voronoi tessellations (see math.lbl.gov/voro++)
Download here Voro 1.2 and unzip it inside the /plugins GiD folder, replacing previous copies, then start GiD and a new menu ‘Geometry->Create->Voronoi…’ will appear
The plugin includes voro compiled for Windows and Linux x32 (the x32 version is able to be run in x64 also)
Note: For Linux remember to set the execution flag to voro++ with the command chmod +x voro++
