I was asked how I built my iPad/writing tablet case. I built it while still waiting for the iPad to come out and it still works like a charm. All you need is an iPad case (I am using this one), a writing tablet (preferably one with a sturdy-ish cover) and some Velcro.
First, see some pictures I just snapped of my case. Then, below the images, I tried to write up the process as well.
If you are right-handed, you will probably want to flip the case upsidedown so that the writing pad is on the right. With the iPad in the case and the case open, put some velcro strips on the right side of the case and on the back of the notebook. I leave a gap between the strips to provide a place to store business cards. See Image 2.
Next, use some more Velcro to to create a strap that will (1) keep the whole case shut and (2) just keep the writing tablet closed without the paper flailing around. You may need to cut the Velcro into the shape you need.
First, make the clasping strap. Put a long piece of Velcro fuzzy-side-up on the back of the case (on the opposite side of where writing tablet goes, not opposite of the iPad). Put only the end of the longer piece of Velcro on the case and let the rest dangle to create the strap. Now, cut some more fuzzy Velcro to cover the sticky side of the Velcro that is dangling. Now you have a strap that is fuzzy on both sides. Make sure you place it half-way from each side of the case.
Next, put a little Velcro at the bottom of the writing tablet cover stiff-side-up. Again, half-way between each side. See Image 3.
Close the case so you are looking at the back of the iPad and put another little bit of Velcro there stiff-side-up. And, again, half-way between each side. See Image 4.
Because everything is half-way between each side, the clasp will keep the whole case shut or just keep the writing tablet closed.
And another feature is that when open the case all the way to only use the iPad or only the writing tablet the fuzzy base of the strap will catch the stiff Velcro on the other side and keep the case sturdily open. See Image 5.
Not sure if any of this description made sense, but hopefully the photos are all you really need to replicate this simple design. Hope this helps!