Hi, it works via plugin command. You create a folder and add individual icon files to that folder. Then you create an event in RPG maker that calls a plugin command where you tell it the input and output folders, how many icons per row, icon size, where to start appending icons to, etc. Then you open a playtest in RPG Maker and interact with an event that has the plugin command and it will combine the individual icons into an iconset according to your plugin command.