That’s how I did it.
http://discourse.threejs.hofk.de/2018/HelperExample/HelperExample.html
http://discourse.threejs.hofk.de/2018/HemiSphere%20nParts/HemiSphere%20nParts.html
from the collection
Collection of examples from discourse.threejs.org
One more example
see also THREEf.js/THREEh.js at dev · hofk/THREEf.js · GitHub
You can easily add letters.