By high request I've created a Boxset with smaller spines. The single book can be removed to only show the boxset.
This image was created using my new Boxset Bundle. This is a premium download that contains 72 mockups. It allows you to create large boxset promos up to 25 books. Read & Download
Amazon-ready 6 x 9 Book Box Set with 3 books. I've made the spines wider (1.75 in.) and some users asked if I could make one without the outer box 🙂 Read & Download
Make it pretty or evil, it's up to you. At last, my 3-book box set mockup. You'll find an optional “horror” backdrop layer with many other customizations. One of my more advanced mockups but I think with basic Photoshop skills you can achieve the look that you want. Read & Download