This is a Minecraft plugin for buying and selling items on multiplayer servers. The focus is to make setting up a physical shop easy for users, but it offers a large amount of customization options for server owners as well. Because the focus is for this plugin to be easy to use for players AND server owners, most of the features are designed for usability. Of course, by adding more features, the plugin becomes more complicated (going against the usability). My job was primarily to design the balance between advanced features and ease of use.