Prestashop Length Width Price Calculator (on the fly)

I have a client that wants to sell blinds and shutters online. They will have Standard sizes which can already easily be added to Prestashop in the usual way. But in addition to this they want the customer to be able to specify a custom width and have a price calculated so they can add to cart. The store owner will need to be able to add new blinds and then set price ranges for them example below: Add blind > add between ranges i.e 1000mm > 1100mm = $200 + Cutting Cost From the end users point of view they would choose the type of blind and be presented with a list of blinds with a view button. When clicked on they would be taken to the standard prestashop product view and would be able to choose from preset sizes (standard prestashop combinations) but then have a tab that says Custom Size from there they would enter width, height, qty, colour, room name and mount type ... it would then calculate on the fly the price and they can add to cart. I have attached a screen shot of what is needed. More details will be given on contact either via phone or Skype.