Arduino Clip Art for interface library

I am writing an open source library to integrate firmata based communication with the Greenfoot visual programming environment. I'm a Phd student preparing a java course. Greenfoot is similar to other environments like etoys or scratch.

For this visual interfacing software I need clip art that can be used in an open source project. For example, LEDs, an arduino, sensors, motors, etc. Via a google search I did not find clip art yet.

Any ideas where I can look for clip art for my interface software?