Is it possible to make a mod and the make an addon mod for it?
I think its not possible to make this.
Yeah it's possible. For Mcreator, any tools you make counts as a mod. With that being said, you can make your add-on mod by simply decide it to be. When you extract mod, choose the modifications that you want to make a mod, extract that. Do it a again, this time choose the modification that you want to be in your add-on. Hope this help.