Okay, I successfully used the latest metro in github to create a nifty LXC tarball named lxc-amd64-k10-funtoo-current-2017-05-13.tar.xz. Our documentation was quite thorough on how to set up and run Metro.
Unfortunately, there appears to be no information on how you use your new LXC tarball. From http://www.funtoo.org/Linux_Containers, we get:
Fantastic, but I'm a little unclear on how to set up this config. Does it need to be created by the root or by a user? I've tried to untar this thing and it ended with some mknod failures. should I untar it into /lxc/funtoo0/rootfs? It is a mystery.
I'm probably missing some steps and I'll update this if I manage to make any progress.