Octadecadiminished pentacontatetrapeton

The bitriangular trioprism or bittip, also known as the octadecadiminished pentacontatetrapeton or oddimo, is a convex scaliform polypeton that consists of 18 triangular duoantiwedges and 54 digonal-triangular duoantiwedges formed from deleting the vertices of a hexagonal triotegum from a pentacontatetrapeton. It is the second member of the bitrioprisms formed from the convex hull of two rotated trioprisms and the only convex scaliform one. It is the second in an infinite family of isogonal triangular dihedral swirlpeta.

It is also the convex hull of a triangular trioprism and its central inversion.

Vertex coordinates
The vertices of a bitriangular trioprism of edge length 1 are given by:
 * ±(0, $\sqrt{3}$/3, 0, $\sqrt{3}$/3, 0, $\sqrt{3}$/3),
 * ±(0, $\sqrt{3}$/3, 0, $\sqrt{3}$/3, ±1/2, –$\sqrt{3}$/6),
 * ±(0, $\sqrt{3}$/3, ±1/2, –$\sqrt{3}$/6, 0, $\sqrt{3}$/3),
 * ±(0, $\sqrt{3}$/3, ±1/2, –$\sqrt{3}$/6, ±1/2, –$\sqrt{3}$/6),
 * ±(±1/2, –$\sqrt{3}$/6, 0, $\sqrt{3}$/3, 0, $\sqrt{3}$/3),
 * ±(±1/2, –$\sqrt{3}$/6, 0, $\sqrt{3}$/3, ±1/2, –$\sqrt{3}$/6),
 * ±(±1/2, –$\sqrt{3}$/6, ±1/2, –$\sqrt{3}$/6, 0, $\sqrt{3}$/3),
 * ±(±1/2, –$\sqrt{3}$/6, ±1/2, –$\sqrt{3}$/6, ±1/2, –$\sqrt{3}$/6).

These coordinates show that a bitriangular trioprism can be obtained as the convex hull of two inversely oriented triangular trioprisms.