Strong, externally smooth structures

A structural kit comprising:

• a) at least one frame member having a longitudinal axis and exterior and interior surfaces, the exterior surface of said frame member having a circular cross-sectional configuration, the frame member further having first and second ends, the frame member having a first recess extending lengthwise from the first end to the second end along the exterior surface of the frame member and parallel to the longitudinal axis of the frame member, the first recess having a bottom wall and an intersecting peripheral wall, the first recess comprising a partial chordal section of the exterior circular surface of the frame member;
• b) at least one fitting having first and second coupling faces, the first coupling face being symmetrical to the first frame member end;
• c) means for coupling the fitting to the frame member with the first coupling face abutting and aligned with the first frame member end;
• d) a panel having interior and exterior surfaces, the panel further having a panel edge which matches in outline and cross section of the first recess, the panel edge has a thickness defined by the exterior and interior surfaces of the panel;
• e) means for securing the panel edge within the first recess;
• and
• f) the thickness of the panel edge equals the dimension between the bottom wall of the first recess and the edge of the exterior surface of the frame member at the peripheral wall so that when the panel edge is secured within the first recess the exterior surface of the panel is even with and tangential to the exterior circular surface of the frame member.