Hi Gaston,

"What sotfware would you use if you wanted to make models like the ones shown here? Could this me made in Moi3d?"
http://www.vectorart3d.com/store/

Many of those particular pieces at Vector Art 3D were made using Silo.
Here's a link to the Silo Forum with info about how they were created.
http://www.silo3d.com/forum/showthread.php?t=8869

Another option for making those 2.5D type of images would be the Aspire program.
http://www.vectorart3d.com/index.cfm/Aspire_Software.htm

Hope this helps, Colin