Does anyone know how to disable not holding an item in your backpack?

I'm making an fps game, and there's one big issue. Whenever I press number 1, 2, or any number, my weapon is gone, and I have my hand. The FOV while holding my hand is different than what is the gun, so I was wondering if I could disable not holding an item at all times, if that makes any sense. If anyone thinks they know what I mean, or what they can do to help, please let me know because this has been stumping me for the past day. I also want to make it so that you can't see the items at the bottom of your screen if that's possible as well. Thanks!

I'm not going to try to give you the script, but rather just an explanation on what you can do. Have an unequipped event that causes you to re-equip the gun. I don't know if this makes sense, I think it does. :P

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Might want to use a hopper-bin instead of a tool, from my understanding you want to have a tool without a handle. As for seeing the item at the bottom left of the screen, just make a HUD/Screen GUI then write up an equipped function that changes the item name or picture (whatever you decide to do) to the equipped item.