Write an article based on this summary:

Create a cone-shaped template out of cardstock. Roll the clay into an 18in (0.32cm) thick sheet on parchment paper. Transfer your template onto the clay. Wrap the template back into a cone shape. Create a series of crosshatches along 1 of the straight side edges. Wrap the clay around the cone, then dampen and overlap the edges. Smooth down the seam. Cut designs into the cone using mini cutters. Wait 6 hours, remove the template, then let the clay finish drying. Use the clay luminary with LED or battery-operated tea lights.
Roll a piece of paper into a cone. Tape or staple it together, then cut the bottom until it is the height you want it to be. Cut the cone along the side edge, then spread it flat. You'll have a shape similar to a semi-circle. Make the cone 8 inches (20cm) tall for a large luminary, 6 inches (15cm) for a medium one, and 4 inches (10cm) for a small luminary. Alternatively, you can find a template online for a cone, print it, then cut it out with a pair of scissors or a craft blade. Place a wad of clay on top of the parchment paper. Roll it into a thin sheet with a rolling pin, about 18 inch (0.32cm) thick. Make the sheet a little bigger than your template. Air-drying porcelain clay will work the best, but ceramic clay or paper clay will also work. You can find both in the clay aisle of a craft store. Avoid using wax paper. It may sound like a good idea, but it will stick to the clay. Keep a set of 18in (0.32cm) thick dowels to either side of the clay as you roll it. This will prevent you from rolling the clay too thin. Place your cardstock template on top of the clay sheet. Trace around the template with a craft blade, making sure to cut all the way through the clay. Leave an 18 to 14in (0.32 to 0.64cm) seam along one of the straight edges of your clay cone. This will make it easier to put it together. If you made your own template, wrap it so that the side edges touch, then secure them with a long strip of tape. If you printed out a template, there may be a flap for the overlap; assemble the cone according to the instructions. Your clay piece should have 2 straight edges and 1 curved edge. Choose 1 of the straight edges, then make a series of Xs along it. This is known as crosshatching, and it should be no wider than the 18 to 14in (0.32 to 0.64cm) seam you added earlier. Pick the clay piece up an wrap it around the cone, with the scored edge on the outside. Dampen the scored edge using a wet finger or sponge, then press the other edge down on top of it. For an even stronger hold, score the other straight edge just before you press it down. Leave the paper inside the cone. You won't be taking it out until the clay dries. Support the cone from the inside with 1 hand while you use your other hand to smooth the seam down. Run a wet paper towel or a wet finger back and forth across the seam until it disappears. Find a set of mini cookie cutters or clay cutters that are between the size of your pinkie nail and thumbnail. Support the cone from the inside as you press the cutters into the clay. Give the cutter a small wiggle before pulling it out of the clay. Don't worry about the paper template covering the hole. Cut as many holes into the clay as you want to. The more you cut, the more light will shine through! Set the cone down upright in a cool, dry area. Let it dry for 6 hours, then carefully pull the paper template out of the clay cone. Allow the cone to finish drying. This can take anywhere from 12 to 24 hours, depending on the type of clay that you used. If you are worried about the luminary collapsing as it dries, place a small jar inside of it. The jar needs to be tall enough to reach the top of the cone without distorting it. The clay will turn lighter in color as it dries. For example, if you used paper clay, it will go from gray to white. Do not use real tea lights inside these. While porcelain and ceramic clay do not burn, the heat generated by the tea lights can cause the clay to crack. The lack of air circulation could also cause real flames to extinguish after a few minutes. Paint your luminaries or glaze them for a nicer finish.