Caps and vendors
Sell surplus weapons and armor for caps
Convert unwanted combat loot into spending money for supplies and upgrades.
Vendors in Diamond City, Goodneighbor, or settlement shops you can access.
Repeat after loot-heavy trips as long as vendors have caps. The loop depends on collected equipment and vendor funds, so it is not a fixed-income farm.
Stop when the vendor's available caps are spent or your remaining gear is more useful for crafting, storage, or equipment than for sale.
Open a guide to find other locations and see what the item is used for.
Convert unwanted combat loot into spending money for supplies and upgrades.