How to Craft
There are two ways to craft. Either you can open your backpack at any time (hold the I key) or interact with a workbench. If you’re using your backpack, you can only craft med kits, gas mask filters and ammo for your air-powered guns, one of which you carry in a third weapon slot. If you want to craft ammo for your two regular weapons—the ones you’ll be using most of the time—as well as throwables, you need a workbench.
Workbenches are only found on the Aurora, the train that acts as your home base, or in safe houses. There’s no sure-fire way to find safe houses other than to explore points of interest, marked by question marks on your map. Safe houses are marked green after you discover them.
Whether you’re crafting from your backpack or at a workbench, the interface is easy to navigate—you just click through the menus to highlight the object you want and hit E to craft it. Provided you have the required components, it’ll be added to your inventory.