Non-Inventory Items are non-fulfilling and non-receiving. And because of this nature it does not show on Picking Tickets and Packing Slips.
There is an option to enable this item to be received and fulfilled during order processing. (Non-Inventory Item > Preferences > Can be Fulfilled/Received).
To enable the option of having the subject item printed in the Printing Tickets/Packing Slips.
1. Go to Setup > Accounting > Accounting Preferences tab.
2. Select Order Management tab > Picking/Packing portlet > and check Show Non-Inventory Items on Printed Forms.
3. Click Save.
A sample illustration is shown below.
After the Order is fulfilled, the related Picking ticket can be generated.