You can use Teddy, a modeling software for kids, to create the models, it produces a nice clay-like shape.

http://www-ui.is.s.u-tokyo.ac.jp/~takeo/teddy/teddy.htm

http://www.puppenheim.org/
http://www.wuerfels-welt.de
Old Game Tutorial: http://www.puppenheim.org/MITutorial.zip
Free Game Editor: http://puppenheim.org/AlienalsWeihnachtsmann.zip
http://www.puppenheim.org/blender_starting_main_settings.txt