A jump with the exact proportions of the launch ramp for snowboarding’s big air event, which will make its Olympic debut in Pyeongchang, does not exist in nature. It must be built. And so, fewer than a dozen times a year, at venues ranging from ballparks to parking lots, impeccably orchestrated teams of engineers, ice suppliers, snowmakers, crane operators, up riggers, down riggers, scaffold designers—you get the picture—do exactly that.