Examples 

We prepared some examples of menus. They are sorted by difficult:

Simple menus:: Menus with minimum features and required knowledges to repeat it by yourself.
Medium menus:: Menus with using some not so difficult features, like variables, or more complex logical structures.
Advanced menus:: Menus with advanced features using, like templates, animations, drag-and-drop, etc.

Attention

Some material names, used in these examples can not work on your Spigot version. We used materials for MC 1.13.

Simple menus 

Name	Depends	Preview
Player stats	PlaceholderAPI with Player and Statistic expansions
BungeeCord servers selector	BungeeCord, PlaceholderAPI with Player and Bungee expansions
Cake shop	Vault and any Economy plugin

Name	Depends	Preview
Casino	Vault and any Economy plugin
Admin panel	Essentials, but you can use any plugin to kick/ban/mute players
Item enhancer	Nothing
Random enchanter	Nothing