Hmm, well the lowest section was 50 miles long by 48" at base and 24" at top. With the same quantity of steel it can make a conic pipe 50 miles long with 142" inside and 146" outside diameter and at the top 71" inside and 73" outside diameter. The conic pipe should same strength as solid cone, but the conic pipe should be more sturdy vs any buckling. If you want a futuric looking Eiffel tower sorta shape which might have more resistence to buckling: the circumference of the conic pipe is 522.38", you could cut this into 4 pieces which about 130" each and form a cross shape, this gives a total diagonal length of about 22 feet. But don't stop there, taper these "fins" to a knife edge this should extend the fins by 3 times the length giving you a total diagonal length of around 66 feet.
But why stop there? If you double the quantity of steel you can combine both shape- the conic pipe in the center with the knife edge fins, this gives a total diagonal length of about 78'.
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