How many times have I tried to make crackers that were crispy just like the kind you buy? Answer: Lots! I lost count of how many times I've tried, but finally I took a recipe and made it my way and it worked.
The recipe called for a cup of butter, milk, vinegar and baking soda, then salt. As I was putting it together, I realized that plain buttermilk would substitute for all the ingredients except for the baking soda and salt. The first batch turned out good, but not crisp. So here's what I did:
To 2 cups of flour, add a half teaspoon of salt, a half teaspoon of baking powder and a half teaspoon of baking soda. Mix it up, then add enough thick buttermilk to make a dough that can be handled on a floured board. Roll it out as thin as you can. I wound up using a pasta machine made for rolling noodle dough. I put the rolled out dough on a parchment paper on a cookie sheet, scored and lightly salted it, then baked at 275 for somewhere between 10 and 15 minutes.
Voila! Crackers. Finally.