The lens is surplus/salvage from a stage lighting device. The effective diameter is about 5". The body of the concentrator is made of tin cans - coffee, beans and condensed milk.

The reticle is located at the junction of the bean can and the condensed milk can.


The 'legs' were then soldered to the can.


Photos of the long-range version of the laser beam concentrator in action can be seen here.
More information about this device can be found here.
Plastic Fresnel lens/irrigation pipe version.
Laser Beam Concentrator Technical Details
Music on a Light Beam - the System Tested