I took a photography course in the 90s and we did some 3D images that you looked at two photos through a viewer or by going cross eyed. The teacher tried to get us to invest in some lenticular pictures but the cost for a 16 year old was just too much. As I understood it back then, they cut your 2 images into very thing strips and then interleaved half of them. I'd not thought of it much since but of course it makes sense that a good photo printer and the right software could make this all far simpler.