My nephew came to visit for his 10th birthday this summer, and what a fun chance to make a cake for him! He is super into Harry Potter (among other things - like guitar and Lego and lots of other books and climbing every tree in sight), and I set to work sculpting bits out of fondant to make his HP birthday cake. Like others before, I made him a spell book, but I customized the decorative elements for my nephew. It was just the immediate family, so I made a 9x13" cake and cut it in half and stacked it to make the book - that was the perfect size for us with plenty of leftovers, and it made a nice, tall cake that looked like a giant tome of a spell book.
Ooh, it was fun making the snitch! It's a big (ping-pong ball-sized) glob of fondant, adorned with very skinny strings of fondant making the decorative parts, which I allowed to dry and then painted with a mix of vodka and gold luster dust. But the wings were the best part! They are rice paper! I cut out a front and a back for each wing piece, laid in a strip of very fine floral wire to give them structure and allow them to bend, and glued the front and back together with piping gel. Then I used scissors to cut strips in the paper to give it a fringe appearance. The rice paper cuts easily with a knife or scissors and is actually pretty easy to work with. I left about 3/4" of wire exposed and that's how I stuck each wing into the snitch.
Here are the wand and scarf. I couldn't think of an easy way to make the scarf alternating colors. I ended up cutting strips of maroon and gold and sort of gently smushing them together. It was pretty delicate, so I'd probably try to figure out a better way for next time.
I brushed bronze luster dust onto the sides of the cake to "age" the pages, but I was a little heavier handed than I would have liked to be. Since the cake was a little cold, it didn't brush on smoothly. I would have been better off waiting until the cake was totally at room temp - or using a lighter touch.
When our rabbi saw pictures of my nephew's cake, she mentioned that her twin girls, turning 6 in November, are huge Harry Potter fans and would love an HP cake. So, come November, I made a pink and purple Harry Potter cake for them! I wasn't sure how the colors would fly: would they be delighted to see their favorite shades, or would they complain that those weren't the house colors for Ravenclaw, Slytherin, Hufflepuff, or Gryffindor? No matter, they loved the cake, and I followed a very similar design - but times two and with some lightning bolts for oomph!