FPS Weapon inventory script help

I am making an FPS game that contains multiple weapons. You can switch the weapons by pressing '1','2','3' on the keyboard. To pick up a weapon, you press 'E'. The default weapon is the players hands(Set on '1'). Doing simple math, there are two more slots available for weapons. There are more than two weapons available to use. I'd like to have it so that I could pickup a weapon to go to slot '2', and then pickup another weapon to go to slot '3'. You will be able to switch back and forth.

The main problem is when I pick up a weapon (Other than hands, set by default), that the weapon in slot '2' switches with the other weapon you pick up. Basically, slot '3' is never being used. I would like to have the weapons to stack up, one by one. Please help! Short, simple scripts would be useful, thanks!

(Let me know if you need to read the scripts)