Making placeable entity but not using any vanilla entities?

[nocot]

Hello, I need a general advice on the entities. Most tutorials found in google on how to create an entity are showing how to make an entity that extends another entity (e.g. how to make  custom mob), but I haven't found anything for making an entire entity from scratch. Do you have any general advice or tutorial on how to make an independent entity physically appear in the world? I already know how to register entity, I just don't know how to make it placeable. Let's say I want to make a moving box. I have the entity properly registered, and it has its own class. I have its model and textures ready. What's next?

[nocot]

Thanks, I'll check it out.