Width and Height Price Calculator Prestashop

We need to modify our shop selling Wallpaper so customers are able to put custom width/height and the price are calculated based on that. These two values (width and height) should be also visible in the shopping cart and on the invoice next to product name - be part of the product description (i.e. Wallpaper 0.54m x 2.10m) and also be visible in the same way in the back office in order for us to enter into our digital printing software. We have a calculator in place but it currently isn't working properly with our web designer leaving us. Currently the calculator works on the basis of 54cm sheets by a custom height so every time a multiple of 54cm happens a new sheet is add for example a wall width of 60cm would need two sheets of 54cm. we know this system is hard but would be willing to settle for a price by square meter system as long as the system gives us the measurements that the customer entered in the back end A sample website of similar calculators can be provided It also should be possible to have in the shop regular products (with no width/height size inputs e.g. for our t shirt collection). Our hosting is on go daddy and all technical aspects are dealt with by you with myself giving final sign off. Contact me for more details although my coding/website design experience is limited