The trust allows trustees to use the items without you present, like an individual Form 4. So if you have 12 kids and 12 brothers, any one of them could take it out of the safe and drive off with it, no problem. Not so with an individual. As far as leaving it to your kids, that is handled in the will, a different instrument. All the trustees share the item if you die.
If you have individual NFA items, you leave them to whomever, on your death they fill out form 5 (also free) to gain legal custody of the item from your estate.