Product Weight on Product Details Page

I'm hoping someone can help.

I have managed to display the product weight on my product pages using the following code:

{$product.weight} {$settings.General.weight_symbol}

I have also added weight changes to individual products (eg when choosing a longer length the weight goes up by 8%).

What I would like is for the weight to dynamically change when these different options are chosen, just like the price changes when these options are chosen.

Can this be done? If so, could anyone assist me with what code needs to be added?

Many thanks.