If you wanna make terraforming easily, you should install WorldEdit (as a mod), or create a minecraft server and install W/e (World Edit) and VoxelSniper (as plugins). There are a lot of tutorials on youtube about how to make good looking terraforming, here you have the ones I learnt from:
(for mountains)
(for floating islands)
I usually make terraforming with voxel, but there's a really good way to make it with W/e:
1. Pick a stick and type the following command:
//brush sphere 12 5. After that, type
//mask 0, so you only place blocks in the air (0).
2. Create the base of your island by typing
//cyl 1 (radius you want, e.g. 5, 7, 8...)
3. Start placing the sandstone spheres trying to get a cone.
4. Once you have the shape, select the area where your island is (
//pos1,
//pos2), replace the sand with another block, stone for example (
//replace 12 1) and then do
//smooth 3 (or any other number).
This command will smooth the terrain (lol).
5. With the same selected area, stand on top of your island and copy (
//copy) it, after doing that, type
//flip and paste (
//paste) the what you copied before.
6. Now you should have a floating island!!!! If you wanna color it, type the command
//brush sphere 5 (radius)
3 (the ID of the block you wanna replace the stone with) while holding a stick and then type
//mask 1 (the ID of the block you wanna replace/colour).
P.S: If you want to see the ID of every minecraft block, press
F3+H.
