I found this on Q&A on some website.. Is the new StarCraftII map editor able to make our own 4th race by combining 3 races different looking and ability etc. together? even more combining with some new units from the editor? (battle.net) -cS)beta Yes, custom races are fully supported, including the ability to choose them from the game lobby while playing melee maps, as long as the mod defining the race is loaded. So can you design your own race,or units within the editor or does a mod have to be created for it?
You can design your own race in Warcraft III's editor. The only real difference we've seen for StarCraft II is you can put the new race in the lobby. (The mod comes within the map editor.)
You will probably be able to put your hunger for customization to its limits with this new map/mod editor. I have never played WCIII or used its map editor but from what I've learned ('im not entirely sure tough) you will not only be able to make changes to unit values but create new values and entries. Same goes for buildings sides and almost everything else. The modded values will be saved in the generated/edited map files internally, so there will be no need to download separate mod files. Expect alot from this editor.
I still use the Wc3 editor to feed my creative hunger, and am constantly suprised at the shear amount of new things I learn that it can do. If the Starcraft 2 editor is better than this, EXPECT INFINATE POSSIBILITIES. (almost)
The editor comes with "Startools" that should let you be able to make models. People have made new models for Warcraft III, so you can in StarCraft II as well. (I believe they had to use third party software to make models; you probably won't have to do so in StarCraft II).
Actually, that's from a Q&A batch .. Not from the battle.net forums They've already confirmed there will be no model editing software in SC2.