Zen Cart price by attribute - width/height entered in text box

Need a module so a client can have his website products priced by attribute. i.e. width is 10cm height is 10cm total area = 100cm2 So if it was £0.10 per cm2 total would work out to be £10 The website visitor need to be able to enter own dimenisons so a tolerance level would need to be added as well. This need to be working well with the backend of Zen Cart Please see the following thread on zen cart forum for more information. <[login to view URL]> ## Deliverables This needs to be done ASAP