The boxes in any ski resorts terrain park can be made quite easily by the owner(s) of a ski resort, or a terrain company can make it first, which can then be bought by the ski resort
the biggest ski resort in the us is big ski ski resort in Montana it is also the second biggest in north America
Sun Valley, Idaho
Brighton Ski Resort was created in 1936.
Tiffindell Ski Resort was created in 1993.
Ski Resort Extreme happened in 2004.
Ski Resort Tycoon happened in 2000.
Ski Resort Tycoon was created in 2000.
There is no ski resort on Mount Everest
The Deer Valley Ski Resort opened in 1981. The WTA created ski trails and facilities during the winter of 1936-1937, but an actual resort did not open until 1981.
The first ski resort in Canada and the 2nd in north America is Mont-Tremblant Quebec, opened in February 1939. source: http://www.monttremblantpropertyforsale.com/mont-tremblant-resort.HTML
It is the largest indoor ski resort but it is not nearly as big as most outdoor ski resorts.