FOSS gamedev and creative worlds

Hi guys
I have a question
How can I make a world which is super flat.The layer above will be dirt with grass while the se cond layer will be just dirt and the layer below that will be just stone.I would want to know how to do it cause i'm making a mod showcase

http://forum.minetest.net/viewtopic.php?id=5977
The "flat" flag has not exactly the layers you want, though. If you really need the exacty same layers then you maybe get what you want by rebasing that against the current Minetest versions: http://forum.minetest.net/viewtopic.php?id=4412