I'm sort-of amazed that I never posted about this before. We made it almost a year ago:
We couldn't find an Othello set anywhere in Cork, so we decided to make one.
I'm sure I had planned an elaborate post giving all the details, but you'll have to make do with what I can remember :) The 'case' is just a cheap cardboard file which opens up to reveal:
The grid is cotton string glued down with Bostik. We wanted something textured to hold the pieces in place, and this works very well. (The sides need to be weighed down to stay flat, hence the cup).
The boxes for the playing pieces are made from thin card, and they fold up with the pieces inside when the set is being put away.
The pieces are made of circular stickers, stuck to the black card, and then cut out.