A true scale model of the Eiffel Tower that was 1 foot tall would only weigh as much as a nickel. About 7 grams, about 1/4 ounce.
The air in a cylinder containing the Eiffel Tower weighs more than the tower itself. The Tower weight is reportedly 9400 tons and air in the cylinder is 11,200 tons at sea level.
If all the iron in the Tower were melted into a single square bounded by the base of the Tower it would only be 6 cm or about 2 1/2 inches thick