I had to do this for school, it's my own creation and was very difficult! I have no pictures, sorry:(
Take a normal folder and cover with duck tape. I used blue, but the original cover showed through. You can be creative!
Now measure how big your school materials are. If the rubber bands aren't long enough, they w't hold anything!
Once you've measured take two rubber bands. I can't really explain how to tie them, so you'll just have to try. Sorry. Tie the rbber bands together.
Now using scissors or a fat needle, poke two holes thru the folder using your measurements for the first item. Now slide the rubber bands thru and tie so they will stay.
Now continue this pattern, changing size and amount of rubber bands for each object.
Once you have finished, tape over the back and front again, so that the rubber bands don't stick out. (And so they'll stay in place)
Now put a name on your folder and you're good to go!