Here are some common methods for making flower pot molds:
Using a plastic bucket as a mold: First, build a frame. Pour cement mortar into the frame, smoothing it with a trowel as you fill. Sprinkle a layer of dry cement on the surface to accelerate drying, then smooth it again. After the cement has slightly hardened, remove the frame. Use a PVC pipe to press out a circular cement block from the still-wet cement slab and cut it for later use. Fill the cylindrical structure with sand and compact it. Remove the cylinder to obtain a cylindrical sand mold. Fill the gap between the sand mold and the cylinder with cement mortar, pouring it until it's almost flush with the sand mold. Insert an iron ring to enhance the structural strength, cover the sand mold, and lay down wire. Continue pouring mortar and smoothing it. Use a water pipe to create a drainage outlet in the center. Place the semi-circular cement block into a plastic bucket. Place the cylindrical structure on its side, scoop out the sand to expose the main body of the flower pot, and vertically attach the semi-circular cement block to the surface of the flower pot, arranging them in a staggered pattern. After attaching, brush on a layer of cement slurry.
Using cardboard as a mold: First, use strong glue to attach paper strips to the four sides of the cardboard to form a cardboard frame. Inside the frame, fix three paper strips vertically to evenly divide the space into four independent small areas. Thread a wire through each independent mold cavity, pour cement mortar into each cavity, and smooth it with a trowel. After the cement mortar has completely dried and hardened, remove the outer cardboard frame and the inner paper strips. Place a paper frame on a plastic sheet, fill the frame with sand, and compact and smooth it. Surround the paper frame with a wooden frame, and pour cement mortar into the gaps between the paper and wooden frames. When the mortar is almost flush with the paper frame, insert a wire frame to reinforce the structure. Cover the entire sand mold with cement, and sprinkle dry cement on the surface to accelerate setting. Lean the square cement column diagonally against the inner wall of the wooden frame. Use a water pipe to make holes in the cement surface.
Fill the wooden frame with sand and smooth it. Pour cement mortar into the wooden frame again until it is flush with the frame. Use a trowel to smooth the cement surface. Once the cement is completely dry, remove the outer wooden frame first, then clean out the sand from the hollowed-out areas.
A general, simpler method: Prepare a flowerpot mold. Apply machine oil to the inside of the mold, pour in a 1:2 cement mortar mixture, tamp it firmly, and pre-drain holes. After 24 hours, remove the mold, first removing the inner membrane, then the outer membrane. The flowerpot is now complete. Alternatively, after pouring cement mortar into the mold, use a tool to knock out the air bubbles in the mortar, prepare a stick and put it into the mortar. When the mortar begins to solidify after 5 hours, pull out the stick to form the drainage hole.