Customizing your weapons and adding new attachable parts to your gear can really help you out a lot in Deus Ex: Mankind Divided. Customization allows you to add muzzle attachments like silencers to your guns, and also improve the performance of your weapons. However, before you can customize your weapons, you need to gather crafting parts, which can be found scattered all over the world.
To customize your weapons, simply bring up your menu and go to the inventory. Select the weapon you want to customize, and select the ‘customize’ option. This will bring you to the customization screen, where you can view all of the changes you can make to your weapons. From here, all you have to do is select the change you want to make, and the game will also let you know if you have enough crafting parts to modify your gun. If you have enough crafting parts, you’ll be able to add upgrades to your guns.
However, do note that upgrades and modifications are permanent, and they cannot be undone. Make sure you’re really committed to the changes you want to make before spending your crafting parts – these can be surprisingly difficult to come by in Deus Ex: Mankind Divided.