zx package Path
Package a project located at the given Path and write the resulting .zsp file to the current directory.
ceverett@takoyaki:~$ zx package code/my_app Packaging code/my_app Writing app file: ebin/my_app.app Wrote archive my_realm-my_app-0.2.0.zsp ceverett@takoyaki:~$
The resulting .zsp file will be signed with your user key for the realm indicated by the project's meta. If you have more than one user for that realm available ZX will prompt you to select a key. If you do not have a private key available for the current user you will need to generate a keypair.
Key selection and signature can occur whether or not the realm you are using exists outside the local system, meaning that it is possible to create unhosted, entirly local realms and manage a set of packages independently of the external Zomp constellations and realms -- occasionally a useful option for development of a large project in a highly restricted security environment (or for people with unusually large pet projects at home).