As I'm working to add custom printing to my application, I've settled on using TMetafile to create the pages, then using it to preview &/or print, but I'm finding the documentation lacking.
Are there any good resources for learning the ins and outs of working with TMetafile and TMetafileCanvas?
The ins and outs of working with TMetaFile/Canvas are more related to meta files than to the TMetaFile and TMetaFileCanvas implementations from my traumatic experience of working with it. Aka, you should rather look for information on how EMF (or WMF) works. The Delphi implementation simply calls windows to do everything as I understand it.
You may wish to be more specific what it is you need to know though beyond a walk through guide on how to do it.