My mind has generated an idea of recreating Super Mario Maker in Minecraft!
It will work absolutely same as the original Mario Maker, even with sharing levels and different game styles to build!
Mods that will be required:
Every mod, marked with (+) will be provided in a special modpack. However, you'll need to install Super Mario Bros. Mod by Jimboom7 because he isn't allowing to put his mod into modpacks. Here is the list: Super Mario Mod, WorldEdit (+), Forge (+) and my special mod, which adds blocks from SMB3 and SMW (+).
How will it work:
Sharing your level: you download a map, build a couple of awesome levels, save it in schematic file, pack it into a .zip archive and send on special e-mail, then I will moderate it and post on a special website.
Playing other people levels: you download a pack, unzip it, place it into .minecraft/config/worldedit/schematics, load it and play!