Prep the base machine

init, up, ssh; apt as needed

Make it small:

Dump the package remnants after install

sudo apt-get clean

For Ubuntu, make a huge zeroed file then remove it so it can compress out:

sudo dd if=/dev/zero of=/EMPTY bs=1M
sudo rm -f /EMPTY

Clear bash history and bail out:

cat /dev/null > ~/.bash_history && history -c && exit

Repackage it

vagrant package --output mynew.box

Stash somewhere, like artifactory :)

Add it to the local box store

vagrant box add mynewbox mynew.box

Trash the builder machine

vagrant destroy
rm Vagrantfile

Use the new box

vagrant init mynewbox