Free Battery Laser Cat Toy

This was a fun build that did two things, it tried to figure out what to do with a basket of almost perfect 9v batteries removed from smoke detectors and to test an idea for labeling 3D prints by pouring high contrast paint into the recesses created by the type tool.

The battery part worked fine and it was found you can get a lot of useful life from a used 9v battery if you can make due with less than 9v. The 3v laser pointer diode and a 500 ohm potentiometer let you run that sucker down to a