Wink . Free ware but not opensource.
Sometimes you need to use MATLAB. There is however no reason your figures should suck. Use Juerg Schwizer’s script for exporting figures into SVG! Then use inkscape!
I’ve abandoned blender for my 3D modeling and am using Alibre free edition, but I found this thread which may help other people interested in using blender to create models for three D printing http://blenderartists.org/forum/showthread.php?t=88121