For a top and two adjacent side faces of a frustum, we consider its truncation by a plane passing through the top face and the bottom endpoint of the ridge, so that the cross section is a triangle. In this paper we present a construction of 3D gadgets in origami extrusions which create such a truncated 3D object using two pleats. For this purpose, we consider the range of the assembly point of the bottom vertices of the side faces, which point determines the directions of the two pleats. We also find a condition for the negative of the gadget to exist.