Custom Size calculator – possible?

Hi all,

Trying out Jigoshop for a new venture, looks very polished so far. I’ve been playing with variable products, but I’d like to know whether it’s possible to have a product that allows the customer to enter a custom size? I would specify the price per square meter (invisible preferably) and the customer would enter width and length attributes – multiple times for multiple pieces – to calculate a price.

Am struggling to work out if this is possible from the variables, so thought I would ask! Many thanks in advance for any help.