We published a tutorial on the visualization of volumetric data using Tomviz in Microscopy Today, and have made a basic user guide available as a downloadable PDF, along with a video tutorial shown below and on the main page of Tomviz in use. We have a mailing list that you can subscribe to, and receive notifications on software releases, ask questions, etc. We also use GitHub issues to discuss bugs, feature requests, and ask questions. There is a tag on the Kitware blog dedicated to Tomviz updates too.

Tomviz 1.3 promotional demo from Hovden Lab on Vimeo.