(a) first and second connector half sections, each having height and width dimensions,

(b) said half sections having front and back sides of generally flat form defining a thickness less than said height or width dimensions,

(c) each of said half sections having a plurality of pairs of angularly related, outwardly extending rod-gripping arms defining a plurality of rod-engaging sockets,

(d) each of said half sections having, on one edge thereof, male and female hinge elements aligned along a connector hinge axis extending parallel to said one edge and positioned centrally between said front and back sides,

(e) said male hinge elements being effectively of generally cylindrical configuration and having axes coincident with said hinge axis,

(f) said female hinge elements being generally in the form of an open-sided hollow cylinder having axes coincident with said hinge axis and each comprising a generally cylindrically contoured wall section with portions thereof extending over an arc of greater than 180 degrees and having an open side with portions thereof extending over an arc of less than 180 degrees,

(g) a pair of said half sections being of substantially identical construction with respect to said hinge elements and being mutually engageable by a snap-together assembly of the female hinge element of each half section with the male hinge element of the other half section,

(h) said pair of half sections, when so mutually engaged, being pivotable with respect to each other from a position of planar alignment to positions of angular relation.