SallyPointer

I'm very new to SquareSpace and am having difficulty setting weights for my products. I make everything to order, so by the time a client has selected from several options there are hundreds of potential combinations. Any one product though will be the same weight for shipping purposes regardless of variants chosen. I can see that I can set size and weight on each individual permutation, but not how to set all variants for one product to the same weight without doing it manually line by line. Am I missing something obvious? Thank you