villager like gui

NBT, and maybe JSON.

incase you don't know what JSON is, this is JSON:

"root_element":{
  "element":value
  "element":value
}

I will test this myself later on because I am also struggling with this.

You might have to either:

- Set the Mob to have Villager AI
- Make custom procedures or a new GUI with a similar layout

-Take the villager's code for the trading system and tweak it after applying it to your custom mob

I'll post later if I find anything that works. You can also directly edit code in Mcreator. Here's a tutorial since I am not good at explaining the technical instructions on how to do that here - https://mcreator.net/wiki/mcreators-code-editor