Kalle Hyvönen of DGK Electronics has created a new Inkscape extension that might be handy for all of us robot builders:
I developed an extension for Inkscape which can create optical rotary encoder discs in any size/number of segments. It currently supports single and two-track (quadrature) encoders but I’m going to add support for gray encoded discs as well.
Link: Inkscape extension for creating optical rotary encoder discs
(via Inkscape on G+)