A flat plus-sign (+) shape has four arms labeled A (top), B (right), C (bottom), D (left). When assembled into a 3D object, which arms become opposite faces of the form?

In a symmetric cross/plus shape, opposite arms always become opposite faces when folded. Top arm (A) and bottom arm (C) are directly across from each other — they become opposite faces. Left arm (D) and right arm (B) are also opposite. The center of the plus becomes one face, and the piece that covers it (if any) becomes the sixth face.