In addition to printing state materials for all of CalTrans, we also do archival scanning. We have something like a 5 year backlog of scanning to do (we hope to be expanding and at least doubling our capability in the next year). Some of the documents we recently received for scanning were plans hand drawn on an onion-skin like paper, and held together with... they're kind of like rivets, but they're rings... not grommets.... but grommets, I guess. They are not meant to be removed, but to best scan them, we need to remove them, and ideally replace them. I'll see if I can snap a picture in a bit. Has anyone come across these before and do you know where to get replacements, or how to remove them without damage?