You can make a book cover to be different from all the others. It doesn't have to be harry potter the directions are general and can be adjusted for another book.
Step 1: Find Cardboard
Find a nice strong piece of cardboard, Make sure it is sturdy
Step 2: Get Your Book
Get your book it does not have to be harry potter the directions can be modified.
Step 3: Sketch the Title
Sketch the title in the closest manor to the way it is written on the book.
Step 4: Add a Sub-Title (if There Is One)
Draw in the same manor as the title.
Step 5: Draw the Subject
Draw the person or Thing on the cover. Draw in as much detail as possible.
Step 6: Add the Background
Add the background.
Step 7: Cut Out the Head Hole
Cut out a spot for your head or eyes. Use as exact-knife. You may have to lift up the cardboard when cutting. Pop it out when done.
Step 8: Paint the Words
Paint the Title in with a matching color. I used tempera you can use any kind of paint. If you are trick or treating you may use waterproof.
Step 9: Paint the Subject
Paint the subject. Use similar colors. Again i used tempera paint. I would recommend it because i went trick or treating in it and it was pouring rain. The paint didn't even bleed.
Step 10: Create a Skin Color (if Needed)
I mixed yellow with white and red to create that color of skin. I would say it is a nice color.
Step 11: Paint the Skin
Paint with the color you just made. Paint in the Lines you drew.
Step 12: Admire
Admire. OK back to work. Think you are done. Nope. Background time!!
Step 13: Add the Background
Paint the back any color of the book. In Deathly Hallows that would be a dark yellow. I used a roller. You can buy one at Joann fabrics. Make sure to cover all.
Step 14: Paint the Sub-Titles
Paint the sub-title with the same fashion you drew it with. Paint it the color it is on the book. In my case Brown.
Step 15: Paint the Details
Add the details. In my case it is a Colosseum.