[Woocommerce] Tailor made products

Hello,

I’m sort of lost at how to achieve what I want.

I want to achieve something like the following, but in woocommerce.

http://www.metaalcenter.nl/MetaalCenter/Order.aspx

First you choose a material (I achieved that)

Then you get to the second step, and that’s where people can choose a premade size with a price defined to it.

BUT, people can also choose a custom size. Which varies per product.

Then it should make a calculation on how much that will cost.

Can anyone help me out?