34 a 34 d wherein each of the edges is connected by a concave edge 36 located proximately to the intersection of any two of the edges 34 a 34 b 34 b 34 c 34 c 34 d 34 d 34 a respectively a plurality of side walls 38 a 38 d may be formed adjacent to the edges 34 a 34 d wherein the side walls 38 a 38 d are aligned generally orthogonal to a plane defined by the step surface 32 the plurality of edges in this example have a smooth transition or radius between the top surface 32 and the side walls 38 a 38 d these sidewalls 38 a 38 d can be arranged to define a downwardly depending skirt for the step surface 32 in this example the side walls 38 a 38 d are interconnected each in the same fashion as the edges 34 a 34 d by legs 56 each having a concave surface 40 respectively located proximate to the intersection of any two of the side walls and extending downward a greater distance than the remaining portions of the sidewalls 38 a 38 d each concave surface 40 terminates at a convex footer 42 the convex footer 42 transitions to each concave surface 40 at a ledge surface 44 formed substantially parallel to the step surface 32 each side wall 38 a 38 d and its adjacent concave surfaces 40 define a cut out generally indicated by the numeral 48 the cutout 48 comprises a pair of substantially parallel edges 50 of the adjacent respective concave surfaces 40 that intersect a transverse edge 52 via a pair of curved corners 54 the above structure of a single leg 56 has been described herein.