Hi Pieter,

I spoke with @████████and we arrived at the conclusion that there is no simple way to accomplish this. The best we can offer are some theoretical approaches of varying cleverness and complexity.

1. Create a new empty repository ("destination"). Export all templates from the source repo and import them to the destination repo. It will now contain only fields that are part of the source templates.
   1. Next, export the entirety of the source repo as an entries-with-metadata-only briefcase (no images). Then import it to the destination repo. If I remember correctly, the briefcase import process should alert you to any fields present on the source entries that don't exist in the destination.
      
      Note that this likely will not detect standalone fields that exist as part of a different template than the one assigned to the entry, because that field will still exist in the destination.
       
2. The complexity and convolutedness go way up from there, so try option #1 first and report back. It's pretty much straight into custom SQL queries/joins we haven't tested out.

Cheers,
Sam