This is the island of Ysmi. It's a small self contained city featuring a mage college. By making heavy use of Noppes' Custom NPC I've been making a populated city. A player can come in sell everything they've collected from their adventures and buy some custom items you won't find in the game elsewhere.

Most of the vanilla shopkeepers are in there.

I have images and posts here,
https://ysmiminecraft.tumblr.com/

This is required,
https://www.minecraftforum.net/forums/mapping-and-modding-java-edition/minecraft-mods/1278956-custom-npcs