Generally, the model can use construction sludge, but other specifications are too expensive to use. It should be noted that sludge is slightly toxic, so attention should be paid to ventilation when heating. The oven is the preferred heating tool, and the hair dryer can be used as an auxiliary repair tool. It is not suitable for making large heating tools, and sludge is expensive and should not be used in large quantities. Generally, when making a sludge model, it is necessary to make the general skeleton of the model and smear the softened sludge on it. After cooling, use carving tools such as carving knives to repair the model. Its advantage is that it is easy to form, can be cut and filled at will, and can show the details of the model well. The disadvantage is that it is difficult to store and transport. Although the greasy after cooling is hard, it is still easy to be bumped by other materials, which requires special attention.