The gun dealer is a good way to make some money, you can place shelves and sell guns to people through those shelves. You can also use the trade menu by pressing E on the player. After that, press "Money" and then "Request Trade". Spawns with a Gun License.
Note: Scamming is forbidden, the Gun Dealer is also not a raiding class and cannot mug or take hostages.
This is the store shelf that you can buy through the F4 Menu, go to "Shop" and you will be able to buy this item. After that, press E and you can add things to your store!