I regularly use a homemade rolling pin when i need to roll out large slaps. It's made out of a long piece of pvc pipe, filled with (casting)concrete. It's sturdy, heavy and dirt cheap to make - all things i find nice for a rolling pin. One needs to be carefull when rolling in from the edge of the slab, as the rolling pin has a tendency to pick up the clay as it's not porous.
For smaller slabs, i make do with a solid beech wood rooling pin. It's Italian, and I think it's ment for rolling out pasta. But i like the heaviness of the pvc rolling pin better.