Unintentionally struck coins on wrong planchets, 17th/18th Century

Hello all,
I'm trying to put together helpful information in identifying 'off metal'  error coins, specifically those  'unintentionally struck on wrong planchets during the 17th/18th Centuries'. There are presently no definitive written guides, though the one that is scheduled to be published next year only focuses on coins of a more modern era.
Collectors shy away from this specialized field of collecting because of lack of reference, and the many forgeries introduced into the legitimate market, mostly be China... and I don't blame them.
I welcome information on helping collectors to identify 17th/18th Century off metal error coins unintentionally struck on wrong planchets, and any personal experiences you may have had with coins in this specialized category.
Thank you,
Dan