Recommendation: I'm looking for quality robes, cloth and armor parts for my little project, please read for details

As you say, some PWs don’t allow builders to use their custom content, which is often not on the Vault.

However, the reverse is usually true of works published on the Vault. Content is deemed open for reuse without permission unless explicitly forbidden (see Guidelines for a minor caveat concerning Migration Wizard).

Many of us are familiar with this, of course, but it may not be obvious to newcomers.