Big Scary Laser
Here's another of my birthday presents: a green laser pointer (wavelength 532 nm). It has a range of up to 500m! It's from laserpen.co.uk. They put a copy of this warning sign into the parcel, and I guess they know why
Rolf, this was a great idea! It's a lot of fun to write with this laser pen.
Read about my experiment to measure a hair's diameter: HairMeasurement