Preheat the oven with a pizza stone at 450F.
In a large bowl, mix the semolina, whole wheat and rye flours. Add the salt, pepper, and olive oil and mix. Slowly add the water, while mixing the dough. Once the dough comes together, transfer to a clean work surface and knead for about 5 minutes. Cover with plastic and rest 30 minutes.
Cut the dough into quarters. Take a piece of dough and run it through a pasta roller to the fourth setting (you can also roll by hand). You can slice the crackers into strips or you can keep them a bit misshapen and rustic looking.
I lined a pizza paddle with parchment for easy transport. Place the crackers on the parchment and transfer to the pizza stone (parchment and all). Bake until lightly browned and crispy, about 4 minutes. Remove from the oven and let cool. Repeat with the remaining dough.
Note: You can add fresh/dried herbs (e.g., thyme, rosemary) or other spices (e.g., red chile flakes) to the dough.