Is there a way to download the customized print format from one instance of ERPNext and upload it locally in my test instance?
Something like downloading data from one ERPNext and then uploading into another, but for Print Format. And using the normal browser interface if possible. (without programming skills or modifying .py files)
It would be best that you store all of it in a custom app and do export-fixtures. Put the custom app in a repo like github, bitbucket, etc. and then you will be able to re use the customizations when you install the app to another site.