OS X El Capitan v10.11.5

In case anyone is wondering if this app works on newer systems, it does for me. I’m using a MacMini (late 2012) 16G RAM. As others have noted, you can export multiple files in nested folders as PNGs or JPGs. Simply drag the export folder onto Preview and use your left/right arrow keys to “animate” the slideshow. Seems like the app was written several years ago yet still works fine. Thank you Expresso Ray.

nyc.blacksmith about Espresso Ray, v1.1