I\'ve archived an artifact as the last step of the build and it\'s available as something like this: https://xxx.ci.cloudbees.com/job/xxx/52/artifact/target/xxx-1.2.1-SNAPSHOT-r
You can use the Copy Artifact plugin. Set it to copy artifacts from the main project, and choose Specified by permalink where the permalink is Latest promotion: this promotion process.
(Note that since the promotion configuration refers to itself here, you cannot add such a promotion in one step: you must add the promotion with no build step, save, then go back and add the build steps.)