I purchased this tool while in Phoenix,AZ at Hobby Lobby, and find it VERY useful:
Dritz Quilting Measuring Gauge 14 in 1.
There are 14 different measurements in this double-sided aluminum tool.
Anytime you need to check a small measurement while carving,
this tiny gauge will be handy. Measurements range from 1/8 of an inch
to 2 inches. It can be found in most sewing or quilting stores.