I asked the same question over on the Apple support community, and the answer was it can't be done. Is there any way to do this? I can't find any 'export' option, or some such. Regardless, I'd rather move these projects to the Mac that contains the full ibrary for safe keeping. Eventhough I've set Photos to 'optimize storage', its library is almost 50 GB and I suspect my two photo albums are partly to blame. I created two photo books on one Mac, but that Mac is getting a little constrained on space (this has now actually become more important, because I can not update to El Capitan because there is not enough space).
