Hi,
I suppose one way to head of any confusion about ownership and onward use of drawing content would be to issue a prospective customer with a secured.pdf of the conceptual or preliminary design in which the file security options are set to prevent data extraction and drawing printing. An additional page outling ownership, contact details, etc could be added to the *.pdf such that any persons subsequently being issued with the file would be in no doubt about ownership of the intellectual property contained within and maybe even a short project history sheet containing any caveats about payments needing to be made in the event that this material is used for onward design development.
Regards
Ken Hume
