Nets are two-dimensional patterns that fold into three-dimensional shapes, so they are a great tool for analyzing and constructing solids. Use the tetrahedron, octahedron, and icosahedron tools to help you examine each shape more closely, and to practice folding each net into a solid. 2. Using the link on the activity page, cut out each net. Fold and tape each net into a three-dimensional solid. Your solids do not need to be perfect.