custom orders

I need code written for an ordering system for custom built furniture... mainly radiator covers. I am currently using zencart for pre-built items, so a plug-in for that will work great. The system needs to allow a customer to choose a cover style, pick a wood species, then most importantly enter the dimensions they need. I am cross referencing prices from an excel chart manually at the moment. If a system that can reference these numbers automatically a lot of entry time will be saved. Each style (3)has about 7 wood species, they are separated by 3 depth ranges then referenced by width and height from the chart. The width and height dimensions are in ranges, so sizes entered within those ranges need to be reference appropriately. Other option will then be provided for customers to choose from, some effecting the price. The system needs to allow multiple pieces to be figured seperately and payed for together through a paypal checkout. I would like to also incorporate other items with this system in the future as well.