This plugin allows you to select and upload a 3D model from your hard drive and place it in the world. The model is then saved automatically in a separate database file (so it will be loaded again after restarting the server).
In order to upload the 3D model, this plugin creates a new custom item which is craftable at the workbench (workbench -> miscellaneous). This item is only craftable by admins, although they can still give this item to regular players.
Be careful when uploading too many models with too many polygons, since this could have a major impact on the performance!