This is a tool I put together to compare wheel offsets for my 1/10 RC drift car. Operation is simple - fully insert the tool into the 12mm wheel hex and press the slider against the back edge of the wheel. The line that the top edge of the gauge lines up with indicates the offset of the wheel. The slider is captured so it doesn't get lost in your toolbox, and the measurements range from 0 to 10mm of offset. See pictures for examples on +2 and +6 offset wheels. 

Printing notes:

• Print the gauge on it's top face, the end without the peg

• To capture the slider, pause the print somewhere between 5mm and 20mm z-height. Install the slider at this time and then resume printing.

• Adaptive/variable layer heights will make the numbers more legible.