We used:
laser module 200 mW
Laser Line Lens 30°
Clear acrylic tube 60 mm OD 5 mm w
Aluminum tube 50 mm OD
Motor Gear 6v 60RPM
Round Holder for 3x 3.7V 18650 Battery
Magnetic Contact Reed Switch
Tested at 5 bar, run time 10 hours.
Seen under water at a great distance and is very effective attracts attention of divers.
We did it just for fun but it proved to be very useful to mark an important place, exit point, etc.
