Free Battery Laser Cat Toy

thingiverse

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 almost nothing and still have lots of battery life left. The last photo is after testing with the other sucker run down. Labeling was another story, I've done the same technique engraving in metal and wood and it worked perfectly. You fill the type with paint and sand the top when it is dry and that cleans up any paint you may have smudged on the edges and polishes the top. For 3D printing when you sand down the top layer it not only polishes up a nice clean top layer but it also exposes rough imperfections which look like gaps along the length for the extrusion. The painted type I did looks alright for a toy or where you need some kind of safety marking but it's far from perfect. At some future date I plan to try this again but I need to experiment with body fillers since I believe that the first step should be to have a smooth polished surface. For the paint something like a disposable syringe could be used since I wouldn't want to get any paint on the newly filled and polished top. For complex jobs an automated syringe painting attachment for a 3D printer might be developed. A clear top coat could then be applied to seal everything nicely. Compared to that last step the electronic build of this project is super easy and most well equipped hobbyist will already have all the components. Make sure you check and adjust the laser for focus before you push it into the lens holder, It's hard to see but the laser is made from two copper pieces screwed together, the diode is on the back piece and the lens is on the front with a spring between. Find a target and carefully check that it focus is right for you. Always remember to turn the pot to min when you install a new old battery as a good 9v will destroy the 3v LED if set to full. Other than the above mentioned painting and sanding this is an easy project and printing should not require any supports. https://youtu.be/7SAgLmJAioU