Roomopolis

StartupEvents.registry('item', event => {
    //Create a custom key item like this
    event.create("test_key", 'roomopolis_key')
        //String location of the template you want to spawn example file is found here data/roomopolis/structures/tiny_room.nbt
        .templateId("roomopolis:tiny_room")
        //The structure is always placed a block behind the block you click on as the player, the height adjustment allows you to adjust the height postion the template is spawned
        .heightAdjustment(1)
        //keyBlock is optional and not needed, if a block is defined here keys will only work on that block
        .keyBlock("minecraft:iron_block")
})