FOSS gamedev and creative worlds

I've been playing with world edit and love the power of it. Now I have an idea in my head that I'd love to try. I have a map from a fantasy world that I'd love to design and build. My question is, is there an easier way to create maps or worlds than manually going in by hand and doing it? Like could I make a CSV type file and feed it to the mapgen to spit out a map?

WorldEdit is a mod which you can use to modify your world with commands.

You can use WorldEdit schematic files (.mts) to import or export structure in or out your world.

You can also use the mcedit editor and make a world/structure or what ever and then convert it.

→ Convert parts of Minecraft maps to Minetest WorldEdit schematics

Example files can be found here.

Could I design a whole surface map in .mts? I don't have minecraft so I have no way of making a mc map to export.

My imageloader mod can help you to load at least the basic terrain layout (flat, no height).

There was also the binvox mod (loading mesh files and converting them to voxels), but sadly its author decided to remove it. Anyone have a backup?

Your mod looks like a great start. I could use world edit and fill in the blanks after that.