Okay, since someone over at craftster asked, I'm posting this pattern here.
R1: ch 1, turn, do sc in next 39 st, 2sc in last ch. Go over to the opposite side of the foundation 40-ch and do sc all the way, with 2sc in last ch. You should have total 82 stitches in one row.
R 2-5: Just go over to the other side immediately. You should have total 82 stitches in one row. hdc in both loops all the way. Turn inside out here.
R 6-8: change colour and do hdc all the way.
R 9-11: change colour and do hdc all the way.
Note: If you want the colour change to be not too visible, you can join the rows with slip stitch instead of crocheting in the round.
Finalize: Turn it outside in again, and sew on the zipper to the top row of the last round, and make sure the zipper is upside down! Next, open the zipper and turn the pencil case inside out. To make it easier, you might want to mark your zipper first, about 1/8" from the edge
Of course, you can change the colours and the number of rows as you like.
I hope it is clear enough. Unfortunately I didn't take any pictures of the process, but the next time I make another one, maybe I will. And then post it here of course.
Copyright Melisa Sriwulandari 2008.