a rectangle
cube There are a great many solid shapes that have only flat surfaces.
cylinder
A triangular prism has 5 flat faces.
Box
There can be no such shape. If there were a shape with n flat surfaces, then if you sliced off one vertex, you would have a shape with n+1 flat surfaces. So it is always possible to add one more flat surface.
A cylinder has 2 opposite parallel flat surfaces.
A sphere
a rectangle
cube There are a great many solid shapes that have only flat surfaces.
A cube
a cylinder
cylinder
Cylinder
A sphere
A sphere
There is no such shape.