"VelocityTools is a collection of Velocity subprojects with a common goal of creating tools and infrastructure for building both web and non-web applications using the Velocity template engine."
An ebuild is available in the experimental overlay: https://gentooexperimental.org/svn/java/gentoo-java-experimental/dev-java/velocity-tools/ It also depends on the version of velocity in the overlay.
Now removed from java-overlay as upstream is long dead.