Nice work! Y'know, you could actually DO that project here by putting down a colored layer, then put a black layer down on top of it. Then, Set the color to transparent, and "etch" away the black to view the colored layer beneath.
Silhouette Letter Icons
I was inspired for these icons by an art project where you water color a gradient and then color over it with black crayon. Then you sketch a design in to the crayon. So these icons kind of look like that.
P.S. Vlasta, could you consider supplying me with a free license for RealWorld Icon Editor? I would really appreciate it.