See:
thinjail.sh
for the thin jail scriptclonejail.sh
for the clone jail scriptvagrant/
for an example of how to use them
This is for FreeBSD users who want to learn how to create thin jails and want the simplest possible ready-to-use script to play around with. It's annotated and meant to be modified. It's for those who want to know exactly what's going on with their system and how it's set up.
This is not for users that are looking for a fully mature solution that does everything and simplifies a bunch of work. There are already libraries that do this well, such as ezjail and iocage.