How to select a shipping box for a particular product based on quantity using Drupal Commerce? I have two shipping rules for a particular product.

Case 1. (Shipping box)

Quantity: 1-12
Width: 6
Height: 6
Length: 8.75
Weight: 3


Case 2. (Shipping box)

Quantity: 13-24
Width: 8
Height: 6.5
Length: 11.25
Weight: 4


When a user purchases this particular product, if the quantity below 12, use Case 1 shipping dimensions. If greater than 12, use Case 2.

Anyone can point out how to achieve this? I'm using Drupal Commerce with Commerce FedEx as shipping service.

There's a tutorial on how to achieve something like this but it uses flat rate and not any shipping box dimensions.
Using the Commerce Box module, for which only a DEV version exists, you can create Commerce Box entities, but that's about it. E.g. it does not add any specific Rules Actions you can use to select the appropriate shipping box, such as based on product items and/or quantities.

However, there is an inspiring issue for the Commerce Fedex module, titled "Allow altering of default package dimensions". And comment nr 17 of that issue contains an interesting patch which allows for package dimensions alterations.