Sometimes you don't want everyone to know you are carrying around your iPad. No one will notice that you are carrying a book, especially if it is a 1970s ex-library copy of "New Zealand in Colour." With a hobby knife, a paper clip, and a bit of patience, you will be able to recycle the very thing you are replacing into a case for its replacement. That could have been said simpler but you get the idea.
Step 1: Find the right sized book
Take your iPad to a second-hand book shop or thrift store and find a book that is the right size. I found the best size was when you set the iPad on the pages of the book, there is about 20mm (3/4") to 25mm (1") all around it. Too small is a problem because the paper won't be strong enough to hold the iPad in and too big is fine, if you like carrying alot of size and weight you don't need. The perfect thickness is when the pages of the closed book are the same or slightly thicker than the iPad. I also chose a book with lots of photos because the pages were thicker which meant stronger and less to cut.
On second thought, why not breath new life into that old Masters thesis as a personalized iPad case? You're probably not going to read it again are you?
Step 2: Draw and Cut and Cut and Cut...
OK, this is the part that gets a bit boring but you don't have to do it in one sitting (as I foolishly did). Set the iPad face down on the first page and trace around it. I used a pen because a pencil might mark the edge of the iPad. After tracing, carefully cut out the first page. Once cut, you can either trace the shape on the next page or use the hole as a guide. It might make it easier to cut the curves with a fine xacto-type blade but after a few pages I switched a heavier stanley blade for everything except the corners.
Another thing to remember is that as you cut more pages, you tend to open the book (as in the photo), and the spine of the book will flatten. When this happens, the position of the holes will change so when you are cutting, make sure the spine is as it will be when the book is closed.
Keep cutting out pages until your iPad sits in the hole and is flush with the first page. My book was about the right thickness so I cut all the pages.
Step 3: Tidy up the edges
No matter how accurately you cut the pages, they won't look perfect. Don't worry, get out your trusty Dremel-like tool and go around the edges with the tiny drum sander bit. I found that the sanded edges tended to spread and made the whole lot slightly thicker at the sanded edge. If this is going to bother you, you could clamp the paper down while you are sanding it. It didn't so I didn't.
Again, make sure you do this with the spine upright so your sanded paper "walls" will be vertical.
Keep trimming until your iPad fits nicely into the space. It may not be able to go all the way into the hole because it gets caught on the buttons, so when you get close, go to the next step and after the spaces for the buttons are made, you can do another trim.
Step 4: Make room for the buttons
Now if you have an iPad 2, you can skip this step because the iPad 2 buttons are on the curves so they don't stick out the side. Mine is an iPad 1 so I had to use the same drum sander tool to make small indentations where the volume/mute and the power button stick out on the side.
Step 5: Insert the remote Power button
OK, so your iPad is happily in your new book-case but you can't turn the power off. No worries! Simply put a paper clip in the right place so the end lines up with the power button and voila! Remote power button.
Step 6: Add a Security Strap
You might be nervous that your new book-case will fly open and drop your iPad onto the concrete. Never fear. You can add a special Security Strap. All you need is enough elastic to wrap around the end of the book. Sew the elastic into a loop, then staple the loop to the back of the book. The staples are only for positioning and it doesn't take much force to keep the book closed. I put the old Library cover back on and it hid the back of the elastic and the staples but if they bother you, you can always attack them with a sharpy or vivid (felt pen).
Step 7: Charge/Sync through the pages
If you want to charge your iPad, simply lift enough pages to fit the cable into the dock connector and you are away!