I want the shipping rate to be calculated based both on the products weight and the Zone. However, I also want to have different weight classes and apply different shipping rate on each one. eg. If the weight is 0-5 kg apply 3$ shipping rate. If the weight is 5-10 kg apply 6$ shipping rate etc.. Is that possible? I understand that I have to use Method 4 to get this done, but I can't figure out how to create those "weight classes". Can anyone help me?