To find weapon mods, you need to find the mod tier boxes located on the islands of the game. You can see where these boxes are by the chest icon on the map. Normally, these are hidden away and require some navigating, and grappling hooking to get to. Then you must carry it back to your storage.
When you are back at your Fathership, top the right of where you dock your ship, there is a place where you can install the mod box. By doing so, will give you its contents which is a weapon mod. You have to go through this process with every mod tier box you have. Though a helpful hint is to remember what mod the weapon is for, as there is no way of finding it afterward.
They are different tiers of mod boxes you can find, as well as different colors. Tier Box One is the lowest, and Tier Box Three is the highest, with the best mods you can get. A standard tier box is yellow, and a special one is green. If you can find a green mod tier three box, you'll be in for one hell of a mod.
Each weapon has four types of mods they can equip. To install a mod, open up your tablet by pressing Select or Tab, go to the equipment page, and select a weapon, and press X, or E.
As we said above, without remembering the name of the mod, you'll have to go through each of your mod slots on your two weapons, and eventually, you'll find the mod. On the left side of the screen, is the stats for your weapon. When adding a mod, these stats will change to red and green. Green is an upgrade when red is a downgrade.
For more Black Skylands coverage, PGG has you covered!