In this guide I show you how to duplicate everything in your inventory (co-op only).
Simple Dupe with Your Friend
You need a tent, a shelf and a friend. Important is that only the second player can dupe everything in that fast way, the Host just has to run the server.
The second player has to save the game then put anything he wants to dupe in the shelf then he has to rejoin. After that, the items still remain in the shelf and in your inventory. Now take everything from the shelf back to you inventory, save your game and but everything back to the shelf and rejoin.
Over the time, you duplicate it. Mean 2×1=2, 2×2=4, 2×4=8 and so on.
With ammo for example it take arround 20min to get max 1000 rounds of one type.
When you are finished, you can fill up the shelf or two shelfs with you duplicated items for the host and you just rejoin to get a full inventory again.