Info can come from posts on the chat boards. Also from manufacturer records. Excellent source for some of the mold records is www.preservinggaminghistory.com

Takes a lot of searching at times to find the right hot stamp, but that's a lot of the fun. Many chips with initials may be just home game sets, sometimes they can be id'd as an old illegal casino operation. Questions and scans on this board produce a lot of results also. Many helpful collectors here.