Sand casting became one of the earliest forms of casting due to its simplicity and low-tech materials required. The metal parts produced by sand casting usually have a rougher sandy texture and usually have low precision. Therefore, various finishing techniques are required to improve the surface finish. These techniques include grinding, filing, hammering and shot peening, polishing, and electroplating. The molten metal is poured into a cavity mold made of natural or synthetic sand, usually bonded with oil or chemical adhesives. Greensand is a mixture of sand, clay, and coal powder combined with water. The resulting green mold needs to be dried before casting to prevent molten metal from exploding. In the industry, sand casting is usually just one of many processes involved in the production of a single metal part. The designed master or pattern is made by the pattern maker. Due to the shrinkage of the metal during cooling, the pattern is slightly too large. This is calculated using a measuring device called the shrinkage law, which is scaled appropriately according to the metal to be cast. The pattern must have a slight taper (called the draft angle) on all vertical surfaces so that it can be removed from the mold without disturbing the sand. A tapered gate is added to the mold so that molten metal can be easily poured into the mold and overfilled. A riser was also added to allow air to escape when the metal enters the mold. The forming box is made of two halves, called the upper mold and the lower mold. Press the sand into two halves, place the pattern on the surface of one of the sandboxes, and push the two halves together. The pattern is then removed and the negative cavity of the object is left in the sand in preparation for casting. Once the sand mold is made, and the profile, gate, and riser are combined, the molten metal is poured into the cavity through the gate. Once cooled, solid metal components can be removed.

　　My Stool Mould is made of very simple sand casting. I chose to use the natural landscape of Caerhays Beach on the south coast of Cornwall to make stools. It would be a good thing to produce stools with a technique that Cornwall was once famous for. During the mining boom, Cornwall had two of the world's three largest mining engine foundries (Harvey 1779-1903 and Copper House 1820-1869). Both of them are located in Hayle, where the Haier River estuary has the excellent sand quality and is very suitable for sand casting.

　　At high tide, the westernmost side of the beach is also completely below the sea surface, so that the sand is well compacted and remains moist during low tide. I have a portable dual gas cooker and I dug it into a ditch in the sand. Below the height of the sand, I can cover the cookware with a wooden board to transfer the wind and reach the highest possible temperature. I used 1kg tin ingots to melt at 236ºC in two old stainless steel soup pots of my mother for about 10-15 minutes. While heating the tin cup, I used various simple tools to carve various shapes and shapes into the sand, such as a 10mm diameter metal rod, a small carpenter for planting seeds, and a kitchen knife. After melting, I poured the tin powder into the mold to observe how easy it is for the tin powder to flow into the cavity and the complexity of the pattern. Three days ago, I simply discovered my sculpting ability and the sand that I can sculpt. I decided to choose a three-legged stool. The surface of the stool is composed of sixteen subdivided triangles. I noticed in the experiment that when I dig a deep hole in the sand, the molten tin will not always reach the bottom of the hole because the groundwater level drops slower than the tide. This will make it difficult to obtain four equal-length legs. Therefore, by making a stool with three legs, even if the length of the legs is not exactly the same, the stool can always be placed flat on the ground even on uneven surfaces. Will shake. The seat surface is like a triangular mesh, and tin can be used most economically to obtain the largest seating area, saving weight and money.

　　I first draw a 400mm equilateral triangle in the sand, divide each side into four parts, and draw a line between each part. Divide the large triangular surface of the seat into 16 smaller triangles by drawing a line between each corresponding mark on the opposite side of the triangle. Then, I picked up the prepared 10mmØ diameter steel rod with a 400mm mark from the bottom, and then pushed it into the sand at one of the three main peripheral corners of the seat until it reached a depth of 400mm. I pushed the bare end of the rod toward one of the opposite corners of the triangle until the sand was compacted and prevented further movement, pulled it back, and then pushed it toward the second corner until it was easy to travel. This movement gives the legs a natural taper and a V-shaped cross-section towards the top of the stool, making the legs inherently strong and as light as possible. I repeated the V-shaped holes on the other two corner legs and then started to carve V-shaped grooves on each mosaic triangle of the seat with a knife. I carefully carved out sand about 20 mm deep from each channel. I must continue to spray the sand surface with a fine mist of water to prevent the sand from drying out and chipping. Once all the triangular channels have been carved and the scattered sand has been blown away, the sand mold is ready to receive the molten tin. The process of carving the shape of the stool into the sand took 45 minutes. I carefully carved out sand about 20 mm deep from each channel. I must continue to spray the sand surface with a fine mist of water to prevent the sand from drying out and chipping. Once all the triangular channels have been carved and the scattered sand has been blown away, the sand mold is ready to receive the molten tin. The process of carving the shape of the stool into the sand took 45 minutes. I carefully carved out sand about 20 mm deep from each channel. I must continue to spray the sand surface with a fine mist of water to prevent the sand from drying out and chipping. Once all the triangular channels have been carved and the scattered sand has been blown away, the sand mold is ready to receive the molten tin. The process of carving the shape of the stool into the sand took 45 minutes.

　　I removed the lid from the first pan, and then carefully poured the tin powder into the mold starting from one leg. Once the tin reached below the top of the leg, I moved to the second leg and poured the tin to the same height. I repeated this step on the third leg, then picked up the second pan and started pouring some slightly hot pewter on the pewter on the first leg. The molten tin begins to flow along the channel, and as the height of the tin rises, all connected triangles begin to flow. I poured a few mouthfuls until the height of the tin was just below the height of the sand, causing a molten meniscus to form on the surface of the tin liquid.

　　After waiting for 10 minutes for the tin to cool, I started digging. I dug out the sand with my hands, pulled it away from the triangular seat and three legs until the sand had no resistance, and then took the shiny tin stool out of the mold. I successfully sprinkled a tin stool with sand on the beach.