non convex tetrahedral bowtie polyhedron featuring 4 reg hex and 12 reg pent with dodecahedra RobertLovesPi.net DIN 6319 C NI Concave and convex washers Elesa A Polyhedron With 120 Faces, Half of Them Convex Hexagons, and Half Isosceles Triangles RobertLovesPi.net Help needed making a convex hexagon Modeling Blender Artists Community Surfaces Concave & Convex. Contrasting Strategy Challenges by Roger Martin Medium Analysis Situs: check vertex convexity