Making a Nazca line was mostly a matter of subtraction, not construction, which is part of why fringe explanations for them have never needed to hold up.
How the lines were actually made
The Nazca desert's surface is covered in dark, oxidised stones sitting on lighter sediment beneath. Removing a strip of the dark stones exposes the pale ground underneath, creating a line that can stay visible for centuries in a region that receives almost no rain or wind erosion. Surveying tools no more advanced than stakes and cord are sufficient to lay out the straight lines and large figures, a point demonstrated experimentally, which undercuts claims that the lines required aerial viewpoints or outside assistance to design.
Reiche's decades on the ground
The German mathematician Maria Reiche spent roughly five decades from the 1940s onward surveying, mapping and personally guarding the lines, at times sweeping them by hand to keep windblown debris from obscuring them, and campaigning for their legal protection before UNESCO inscribed the site in 1994.
Damage in the present tense
The Pan-American Highway was built directly across several lines in the twentieth century. In December 2014, Greenpeace activists left permanent footprints near the hummingbird figure during a publicity display, drawing international criticism and a Peruvian prosecution, a reminder that the lines remain physically as fragile now as when Reiche started sweeping them.