defined by three sides 203 a 210 b and 210 d with two of the sides 210 b 210 d preferably being of equal length triangular strip 104 is defined by three sides 204 a 210 c and 210 e with two of the sides 210 c 210 e preferably being of equal length lastly triangular strip 105 is defined by three sides 205 a 210 d and 210 e with two of the sides 210 d 210 e preferably being of equal length the first strip 101 also referred to herein as the u201c quad u201d strip is a triangular strip of rod material having a preferred angle 201 of approximately 92 u00b0 the two other angles in the isosceles triangle of the first strip 101 are each approximately 44 u00b0 it is preferred that the first strip 101 defines the primary casting plane i e the plane on which the guides are mounted since it is the most stable of the planes formed by the triangular strips the second and third strips 102 103 also referred to herein as the u201c penta u201d strips are each a triangular strip of rod material having a preferred angle 202 203 of approximately 73 5 u00b0 the two other angles in each of the isosceles triangles of the second and third strips 102 103 are each approximately 53 25 u00b0 the second and third strips 102 103 help to stabilize the primary casting plane defined by the first strip 101 they can have non squared opposite flats and by volume tend.