Enable Liberty.SC2Campaign under dependencies and then take a look at the Healing Potion items, those are items with charges, too. Just modify them to suit your needs.
Edit: Be careful when you use Talon0815's trigger, because it will remove the scrap metals nonetheless, when you use the ability and you only have 1 or 2 of them.
Well, there is no trigger that allows you to do that. Maybe you can do something with the trigger that allows you to move items to different inventories.
Enable Liberty.SC2Campaign under dependencies and then take a look at the Healing Potion items, those are items with charges, too. Just modify them to suit your needs.
Edit: Be careful when you use Talon0815's trigger, because it will remove the scrap metals nonetheless, when you use the ability and you only have 1 or 2 of them.
Well, there is no trigger that allows you to do that. Maybe you can do something with the trigger that allows you to move items to different inventories.
You could make the meat a consumable item with 1 charge and just remove the ability from the unit.