These are sanded Beechwood rollers and slats used to help roll out clay. With the roller and a pair of slats, one can easily roll out pieces of clay to 1 cm (flat slats) or 2 cm (slats on the side) with the combination of the wooden clay slats and roller.
HOW TO USE
You place an amount of clay between the slats and roll the clay roller over the clay repeatedly until the clay has flattened so much that the roller touches the slats. If you lay the slats on their narrower sides, you can roll the clay about 2cm thick. If you lay the slats flat on their wider sides, you can roll the clay to about 1 cm thick.