I got my PE in '95 and started moonlighting a couple years later. Three years ago my employer decided this was not allowed. At that time I was getting 1/3 to 1/2 of my income from moonlight work, so I quit them and went solo full-time. I'm now earning triple what I made then, and still working...
If you're only trying to measure distances of a few feet, why not try a Leica Disto? It's essentially a commercial-off-the-shelf hand-held laser interferometer that runs on (4) AAA batteries. It has a range in air of 100 meters and is accurate to 1/8". It reflects a red laser off a surface...
