God this would help. There are clunky solutions out there it seems but if they don't integrate with the final product count shipped and tracked via Shipstation it still becomes a headache to have to manage another system. PLEASE Shipstation add this functionality. You will help so many of your customers who have multiple parts in a product.
One option to consider is SKUSavvy which provides package materials tracking for orders as well as providing a package size suggestion during fulfillment. SKUSavvy uses ShipEngine (API behind ShipStation, same company) so you get the same rate information while adding full support for purchasing, warehouse & bin locations, as well as visual pick-pack-ship operations.
Works natively with Shopify too pull over and update all locations, products, inventory, customers, and orders.
Thanks so much for providing this solution that has worked for you! Your participation in the community is greatly appreciated 🙂
This information could very well be a giant help your fellow community members!
I think this could be as simple as allowing us to run a report to see which boxes we used for shipping based on the dimensions selected when we chose carriers and print shipping labels.