I decided to make my own valve core tool that was less likely to be lost or stolen.  That turned out to be incredibly easy.

Clos-up Photo

I discovered that I could make my own Schrader valve core tool in about a minute and at practically no cost.  All I needed was a little section of 3/16" brake line ( which our shop always has plenty of) and a cut-off wheel to cut a small slot with. 

For a good fit I chamfered a little off the diameter on the end that fits into the valve stem.   It's not pretty, but it gets the job done. 

Related Tips:

Underhood Work on Light Duty Trucks

Extracting Broken Schrader Valves



Always wear safety glasses when cutting or grinding.