This case took less than 10 minutes to put together and depending on your skills, it will take you about as long.
Note, this will not make your device ready for deep sea diving!
Step 1: Materials
1 SCUBA suit leg
1 nook or iPad
Step 2: Sew the Bottom
Then you want to turn it inside out and sew the bottom in a straight line.
I chose to use the portion that had the knee pads for a cool look.
Step 3: Sew the Top
Then, with the material still inside out, sew the top corners to prevent the device from slipping out.
If you felt like being more eloquent , a flap and a piece of velcro would look really good here.