I did a locket for my daughter a couple years ago, I picked up an auxiliary focusing device for the DII and made reductions from 35mm to Silver Gelatin FB (Galerie) paper. The negatives were one of our dog playing tag, and one of my wife and I when we were dating.

Originally I thought contact prints from 35mm would be nice. But compositionally, I found the two pictures and had to use the full frames - so reduction was the only option. And there really weren't any better pictures to use.

So in case you want to write a sonnet or poem or other love story, you could write it in calligraphy, decorate it, and then photograph it. If you don't have the "reduction" capability on your enlarger... You should plan to contact print it. So then the trick will be to shoot with the camera, not so "macro" close. Plan the shot to fit the locket as a contact print.