Thanks for that Artcfox!
It'd be good if Uze can fix the forum so that that users can upload archive files both ways as the way I attempted restricted the file types and made it seem it wasn't an option (without renaming the file extension into something it accepts). I attempted to upload the files via the thread reply options.
GIMP "selection to row of tiles" plugin
Re: GIMP "selection to row of tiles" plugin
I expect it should be possible to streamline this process further by writing a new plugin that fully automates the steps in the guide, or at least the steps after creating the guide grid.