 ### Deltohedron

Principal forms of the isometric system: deltohedron ### Dihexagonal Prism

Principal forms of the hexagonal system: dihexagonal prism ### Dihexagonal Pyramid

Principal forms of the hexagonal system: dihexagonal pyramid. ### Ditrigonal Prism

Principal forms of the hexagonal system: ditrigonal prism ### Dodecahedron

Principal forms of the isometric system: dodecahedron. ### Forms

Showing different types of forms or shapes: rectangle, right triangle, acute triangle, and obtuse triangle. ### Hexagonal Prism First Order

Principal forms of the hexagonal system: hexagonal prism ### Hexagonal Prism Second Order

Principal forms of the hexagonal system: hexagonal prism ### Hexagonal Pyramid First Order

Principal forms of the hexagonal system: hexagonal pyramid. ### Hexagonal Pyramid Second Order

Principal forms of the hexagonal system: hexagonal pyramid. ### Hexoctahedron

Principal forms of the isometric system: hexoctahedron. ### Hextetrahedron

Principal forms of the isometric system: hextetrahedron. ### Lyre

"Two forms of the old Greek lyre." -Foster, 1921 ### Octahedron

Principal forms of the isometric system: octahedron. ### Pyritohedron

Principal forms of the isometric system: pyritohedron. ### Rectangular Prism

Principal forms of the isometric system: rectangular prism. ### Rhombohedron

Principal forms of the hexagonal system: rhomohedron. ### Scalenohedron

Principal forms of the hexagonal system: scalenohedron ### Collection of Sewer Cross-Sections

"A conduit or canal constructed, especially in a town or city, to carry off superfluous, water, soil,… ### Shapes

Four different types of forms or shapes: right triangle, isosceles triangle, rectangle, and circle. ### Tetragonal Trisoctahedron

Principal forms of the isometric system: tetragonal trisoctahedron. ### Tetrahedron

Principal forms of the isometric system: tetrahedron. ### Tetrahexahedron

Principal forms of the isometric system: tetrahexahedron. ### Trigonal Prism

Principal forms of the hexagonal system: trigonal prism ### Trigonal Trisoctahedron

Principal forms of the isometric system: trigonal trisoctahedron. ### Tristetrahedron

Principal forms of the isometric system: tristetrahedron.