Just for test :)

Make 123 & meshlab are free
http://www.123dapp.com/howto/make
http://meshlab.sourceforge.net/

All by default! All in OBJ format from Moi to the end : can be the same in STL

Make 123 is an incredible Slicer!
Meshlab just for see the result : (for example Wings3d can't do in reasonnable time if it can ?) http://www.wings3d.com/ free
Blender can also but with Meshlab nothing to! do :) http://www.blender.org/ free

Have fun explorations!
Moi


Make 123


Meshlab