Here is a super simple solution, with super cool results. Upon my recent shop organization efforts, I decided to hang my wrenches on the wall. I bought some cheap metal racks from the hardware store, mounted them to a piece of plywood painted the same color as the garage wall, and attached them to the wall (at the studs of course :-). 

I stepped back and thought "How am I going to tell them apart?" So I used xDesign to make some labels, and 3D printed them. I switched the filament from black to white at the precise moment when the letters began to print. Now I want to label everything!