Indoor ski slopes tend to be short because they’re expensive to build. In 1986 Nobuyuki Matsui proposed a space-saving solution: Arrange the slope in a helix or a figure eight around a support tower that contains an elevator. Skiers can ride to the top and enjoy a long continuous run back to the bottom. To reduce cooling costs, the whole thing can be built underground (with a ski lodge at the top) and all the snow-making accomplished within a special enclosure that works its way down the slope.
“In order to simulate actual outdoor skiing conditions, provisions are made to vary the steepness of the slope from place to place. In addition, facilities are provided to produce random simulated moguls or an entire mogul field. Thus, during one run of the slope, most, if not all, of the conditions encountered on natural outdoor slopes may be simulated and incorporated into the run.”