I have been thinking to make wallet and have looked around for tutorials and found these useful links:
finished size when folded: 21x10 cm (8.5"x4")
finished size when opened: 21x20 cm (8.5"x8")
2 full width pockets
1 zippered pocket
6 card slots
(Azaidris used light weigth interface for card slots and medium weigth for wallet body and it worked well.)
This has a section on "Tips on cutting and ironing fusible interfacing". Suggest you read before making any wallet. :)
With instruction on how to sew zip. It used turn & top stitch technique.
4) Quilted Wallet - http://darnkat.wordpress.com/quilted-fabric-wallet-tutorial/
Looks like it is about the same size as 1) but without zippered pocket, 6 card slots, 4 half width pockets and 2 full width pockets.
(Azaidris used heavy cotton so she didn't use batting and it turned out great.)
Similar size as 1) but tri-fold. 1 zippered pocket and similar card holders as 3).
Zip closure with external pocket. I have looked a few times, didn't find card pockets.
(thanks to nojie#craft for reminding me of this post, her experience is to use the thinnest interfacing.)
http://www.pinbu.com/?uid-276569-action-viewspace-itemid-110269 with additional notes in English here: http://anic-lohas.blogspot.com/2011/07/sew-along-patchwork-wallet-week-2.html
Many more links here but I haven't looked carefully yet:
Dear Crafters of the above links,
Thank you very much for sharing these useful tutorials, let me know if you don't want to be linked.. Sorry that I didn't first ask for permission...