You can add new skyplatforms with the /newskyplatform <height> command, with height beeing something divisible by 100. Each platform has a size of 100x100 blocks and can be expanded by first trying to dig (and thus updating) the chests in the middle of the walls and then right-clicking the chests. Diffrent types of platfors are offered, so you can add a small "ocean" or a wheat field if you like.
The /spawn command brings you back to the initial platform at 0,0,0. It may be necessary to type /spawn several times if you're creating a new world and falling down. The inside of the initial skyplatform looks like this:
The mod is still experimental and may contain bugs.
Plans for the future: Adding machines (cobble generator, ore extractor, greenhouse) so that all materials from default become available. After all you can't dig most of them in here.
Download: https://github.com/Sokomine/skyplatform/zipball/master
Browse code: https://github.com/Sokomine/skyplatform
Depends on: default
License: GPLv3