Roll sheets of blocks up into spheres.
How to use this filter:
1) Use PNG to Blocks filter to import a flat horizontal map.
2) Use Spherify filter. The way is works is you specify a selection box with the image as the base, and the height equal to the picture width divided by 3.14. Basically create selection box with the picture, then drag it up over empty space for about 40 blocks for a 200 wide image.
3) Run the Spherify filter
MCEdit Filters >