Bifrustum

Set of bifrustums
Example hexagonal bifrustum
Faces	2 n-gons, 2n trapezoids
Edges	5n
Vertices	3n
Symmetry group	Dnh, [n,2], (*n22)
Dual polyhedron	Elongated bipyramids
Properties	convex

An n-agonal bifrustum is a polyhedron composed of three parallel planes of n-agons, with the middle plane largest and usually the top and bottom congruent.

It can be constructed as two congruent frusta combined across a plane of symmetry, and also as a bipyramid with the two polar vertices truncated.

They are duals to the family of elongated bipyramids.

Forms

Three bifrustums are duals to three Johnson solids, J14-16. In general, a n-agonal bifrustum has 2n trapezoids, 2 n-agons, and is dual to the elongated dipyramids.

Triangular bifrustum	Square bifrustum	Pentagonal bifrustum
6 trapezoids, 2 triangles. Dual to elongated triangular bipyramid, J14	8 trapezoids, 2 squares. Dual to elongated square bipyramid, J15	10 trapezoids, 2 pentagons. Dual to elongated pentagonal bipyramid, J16