I have a client who is looking for a coffee table (18" tall) that she can raise to 30" tall. It will have metal legs and frame, the top will be 3/4" MDF with hammered 20 ga. sheet that has a faux copper finish. Any ideas for this? I've thought sq. tubing (drilled) within sq. tubing with a stop and some pin for holding it tight. Is there some sort of "elbow joint" out there, etc? Thx for any input. Cat