I've been working in various shops for years and I often run across unlabeled shelves of material that have different thicknesses. What's a shop rat to do?
This simple measuring tool fits in your pocket or a tool drawer and circumvents using the measuring tape, which is less accurate and more work for quickly determining the depth of a piece of wood in the scrap bin.
Step 1: Open up Illustrator and make a Rounded Rectangle
If you have another vector-editing program other than Illustrator, you can replicate these steps in your program of choice.
Use the Rounded Rectangle tool, make a 3" x 2" rectangle. Set the stroke width to .001 for laser-cutting (or whatever your laser-cutter requires for vectors). A 3-inch by 2-inch piece piece of acrylic comfortably fits in your pocket.