A convex polyhedron is formed from planar polygonal members, wherein aligned sides of adjacent abutting polygonal members meet to form edges of the polyhedron. A flexible polycarbonate plastic joining tab fits into slots in the centers of sides of adjacent polygonal members to enable adjustment of the dihedral angle between the adjacent polygonal members. A supplemental source of support such as hook and loop strips are used to fasten joined polygonal members securely in place at a desired alignment and dihedral angle. The polygonal members have mirrored interior faces which impart infinite internal reflections within an interior of the polyhedron, wherein one of the polygonal members is a two-way transparent mirror serving as a viewport, allowing a user to see into the infinitely-reflective interior of the polyhedron.