How to: conditional shipping based on custom product field

Hi,

I’m running a shop where customers can order greeting cards. They can ship them to their own address and use them whenever they want. There’s a fixed shipping method involved for this with costs of $5.

Now I want to offer a service where I write handwritten personal texts on the greeting card and send it for them towards the person they want. This is a different shipping method than I normally use.

I’ve added some custom fields to the products that the customer can select and fill out with the handwritten text that I need to write down. But when they select this option I want the shipping method to change from $5 to free. Because the extra service adds a $3 fee to the the product.

I’ve looked at many plugins that offer to add custom fields to WooCommerce shop, but I can’t find any one of them that offers conditional shipping based on a custom field.

Any help pointing towards plugins / solutions would be greatly appreciated.