How can I set up different package sizes for shipping calculations?

[AppleSauce999]

There needs to be a warning in the homepage of your account that says “Shipping carriers base prices on weight and volume, since we know you aren’t going to change platforms, we simply don’t care. But we do want to warn you that by setting a default volume (its a default volume, its not a default package) the rates that your customers pay will be significantly less than what you have to pay if they buy more than one item, or if the item they buy is larger than the default box. This will cost you money, but we don’t care, because why should we? We are Canada’s second largest stock, so there’s that.”