6 models wearing 2 sets of bathing suits, or a total of 6 * 2 = <<6*2=12>>12 trips wearing bathing suits.
6 models wearing 3 sets of evening wear, or a total of 6 * 3 = <<6*3=18>>18 trips wearing evening wear clothes.
Altogether, there will be 12 + 18 = <<12+18=30>>30 trips up and down the runway.
At 2 minutes per trip, all of the trips will take 30 * 2 = <<30*2=60>>60 minutes to complete.
#### 60