Once in a while I found myself with some free time between projects and one way to keep the design nerve active is just to create my own version of some ISO 7000 icons for use in equipment.
This is a great way to practice techniques and turnarounds that will help me to have a better approach when facing real graphical challenges.
The ISO 7000 database provides a collection of graphical symbols which are placed on equipment or parts of equipment of any kind in order to instruct the person(s) using the equipment as to its operation. The original set of icons includes symbols for all types of equipment, from automobiles and home entertainment products to earth-moving machinery.