I made a case for playing cards from the instructions in Al Strohlman's "The Art of Making Leather Cases Vol. 1" I used Bicycle playing cards for the pattern. The pattern worked out pretty good. The only thing you have to be careful of is stitching the sides, if they aren't lined up right the cards fit a little tight.
If you make your own case be sure to post pics.
Here's a link to the one I made.