After trying numerous store-bought blade- and bit-height gauges, I came up with my own simple version that works great for multiple tools: tablesaw, router table, plunge router, etc.

The hardwood base holds an upright—grooved vertically to hold a sliding dovetail. Size the mating dovetail on the sliding gauge so it slides freely. Attach a self-adhesive rule to the face of the dovetail. Then drill a 316 " hole, 34 " deep in one side of the dovetail to fit a ballpoint pen spring and a small dowel. This gives the gauge a friction-fit to hold it at a set height.
—Junior Strasil, Falls City, Neb.