We’re building a new Shopify Plus site and had planned on improving our picking system by adding bin numbers to the standard packing list template. But it looks like there is no support yet for adding liquid code to call metafields…am I reading this right?
https://help.shopify.com/en/manual/shipping/setting-up-and-managing-your-shipping/packing-slips-variable-list#line-items-in-shipment-variables
Hoping for clarification and/or work around suggestions!
This is actually doable! I have a client who had exactly the same need.
The syntax is like this:
{{ line_item.product.metafields.location.value }}
You do not use the namespace and must append with .value.
Learn more at https://community.lucidcommerce.co/c/maybe-helpful-for-others/how-to-add-additional-information-to-invoices-and-packing-slips-with-metafields.
Amazing! Couldn’t hope for a better answer! 
Hi @brandpilot ,
We have a custom app that creates the order metafields using order webhooks making this process very easy. Your bin locations can be imported via CSV or using familiar Shopify admin search.
The app can also print completely custom packing slips. Let me know if this is something you would be interested in.