I'm currently working on Sabayon Vagrant/Virtualbox/VMware images, its still in alpha, here the links for those who are interested: https://github.com/mudler/sabayon-packer
The packer templates defines how to assemble the Sabayon images, the entire process is automatized and the Vagrant images can be found on vagrantcloud (now it's called Atlas) Vagrant images @ Atlas: https://atlas.hashicorp.com/Sabayon/boxes/spinbase-amd64 if you wants to put your hands on it, we have packer inside Entropy, it's in the limbo repositories for now. Cheers
