Net wt and gross wt calculation for export business

How it would work? 1) User adds base product with net wt and gross wt. 2) When user adds multiple products in a carton (for e.g.) the net wt and gross wt of total carton is calculated. Why it is needed? Because exports are charged on the basis of weight and a lot of time gets spent to calculate weight for each shipment. What does it need? It needs multi unit feature to be already present in the software.