### 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.