Turn your cheap laser pointer into a line laser using a Lego!
I've seen stuff on the web where people turned the point generated from a laser pointer into a line for use in DIY laser scanning of 3D objects by aiming the beam through acrylic or glass rods, wine glass stems, or fresnel lenses. It occurred to me to try using the little transparent rods that Lego sells, most commonly as the light saber accessory in the Star Wars sets. The diameter of the rod is about the same size as the beam.
I rooted through my son's Legos and found blue, green, red, and yellow light rods to try. Everything worked well except for the yellow for some reason; that turned out really wide and faint. Watch out for bubbles. Not all the rods are perfect inside.
I bought a laser pointer for $1.99 from Frys and created a mount for the laser and the Lego as a proof-of-concept.
The mount will probably change since there are no screw holes to help with mounting or anything like that. Right now there is a base for the laser pointer and the Lego. I put a little notch for the edge of the cap on the pointer to fit into. The top piece is short so that I have access to the button.
Someone suggested using filament. I think this is a great suggestion, since ABS filament is the same stuff as Lego. Actually, I had already tried this with a piece of 1.75 mm filament that I had, and it worked - but not very well. It came out even fuzzier than the yellow lego that I tried. Optically, the filament looks pretty clear to my naked eye, but it may not be as clear as the normal lego. Also, it is significantly narrower than the 3.1 mm Lego sword, so I think some of the beam is going around.
If anybody can try this experiment with a piece of 3mm transparent filament, I would love to hear the results!
There is something aesthetically pleasing about the thought of creating a solution completely from 3D printing material.