I stacked two cakes with chocolate icing in between and all around them for this Harry Potter Cake. I colored the fondant green (didn't mix in the color perfectly so as to leave a bit of a swirling colors effect) and laid it over the "spine" and "front cover". I rolled out another piece like a snake, and wrapped it around the bottom to make it look like the back cover.
I colored in the pages with white royal icing with a leaf tip to make it look kinda wrinkly. I cut out two pieces of fondant, one as the pensive and one as Harry and Dumbledore's outline, and carved the picture onto them using a toothpick. I outlined with black icing color and the toothpick. Then I painted the fondant like a watercolor, using icing coloring and a small bit of gin as the paint. The carvings kept the color from running outside the lines. I placed the fondant artwork on the cake, wrote "Harry Potter" and "JK Rowling" using purple royal icing, on the front and spine.
I dipped a toothpick in black icing coloring with a tiny bit of gin to make the subtitle. To finish, I took a bit of green and yellow coloring mixed with a bit more gin, and swirled the lightly colored mixture all over the cover, and that really just made it look finished. Although the thick store-bought fondant wasn't exactly the best tasting, the chocolate icing underneath made this cake delicious. It served about 12 people.
**the reason I used gin to paint with is because websites I visited said you shouldn't paint fondant at all, but if you did, you had to use gin because water wouldn't stick to the icing. So I used the gin, but I think water may have worked fine too. Painting fondant, I found here, works fine.