First find the amount of material needed for one skirt: 12 feet * 4 feet = <<12*4=48>>48 square feet
Then multiply that number by the number of skirts to find the total material used on the skirts: 48 square feet/skirt * 3 skirts = 144 square feet
Then find the total amount of material she uses for the sleeves: 5 square feet/sleeve * 2 sleeves = <<5*2=10>>10 square feet
Then add the amount of material she uses for each part of the dress to find the total amount of material: 10 square feet + 144 square feet + 2 square feet = <<10+144+2=156>>156 square feet
Then multiply the total amount of material by the cost per square foot to find the total cost: 156 square feet * $3/square foot = $<<156*3=468>>468
#### 468