Papier, potlood en Inkscape.
http://inkscape.org/
Gepubliceerd onder de GNU General Public License.
GNU GENERAL PUBLIC LICENSE Version 2, June 1991 [2]. In short, this means you are free to use and distribute Inkscape for any purpose, commercial or non-commercial, without any restrictions. You are also free to modify the program as you wish, but with the only restriction that if you distribute the modified version, you must provide access to the source code of the distributed version.