what would be the easiest way to implement 2 input fields for width and length, and assign price for lineal meter in admin. So when customer input desired sizes it calculates subtotal price on the fly.
The subtotal should be = (Width + Length) x 2 x Price
Other than using option combinations you are looking at custom development.
If you have set sizes you can use drop down boxes and option modifiers, if it is totally any size input from customer you need it custom.
I was almost sure to get that type of explanation.
Just curious did somebody make similar thing on CS CART before? Or may be there is already paid addon? Would be nice to see the example.