While searching for a csg solution for three I noticed that there is no built in functionality to do CSG in three.
After some research the libs, mentioned above, from @manthrax seem to be the most recent.
Are there any plans to add this or another lib to three?
Coming from Babylon I miss this feature.
Adding an existing external lib like THREE-CSGMesh only means it is copied in examples/jsm/libs and then a new example is added. Similar was done for the physics examples that you ammo.js or cannon.js.
In any event, there is an ongoing discussion at GitHub about this topic: