The glowing resin in Fallout 76 is needed to modify weapons, so this guide will show you a few places where you can find it. It is usually found at the base of trees and looks like a large lump of glowing orange slime.
Resin map
1. The beginning of the Light
While searching, avoid buildings and urban areas - instead search those places where there are many trees - for example, in the southeast.
2. Mountain ranges of Emmetta
This site, located a little further east of Whitespring Station, is a nuclear waste dump, so there may sometimes be glowing resin in the trees around it.
3. Whitespring Station
There are also resin trees at Whitespring Station.