Manage the price of item as per size entered

Hello, We have a modular kitchen business and we have raw material like Ply etc so I want the price to change as per the Length and Width of the board. Maybe something like I make an Item Template ‘Board’ and then make Variant with options Type (Ply, Particle board, MDF) and ‘Size’ In size, I should be able to be enter Length and Width. Taking all these factors it will display price. Also where can I enter the Cost per mm or inch. I would want to enter custom variants in every project
(Something like this)

please refer to this.

Thank you for your response
I’ve tried but its not working…
Basically I want to manage prices as per entered Length and Width and it should be shown in quotation
Eg: price of item (ply) determined like (L*W)*Rate