Laser-Run Gun Simulator

In obstacle course racing and modern pentathalon, one of the challenges is to use a gun "simulator" to shoot some targets. Of course, this happens after running, so your hands are shaking!

Buying a proper simulator is pretty pricey, and there seems to be a lack of open source alternatives. So here is a laser simulator that mostly complies with the UIPM's regulations. It's a bit undersize for pentathalon, and the laser module is uncertified, but other than that it's pretty close. 

What is a Gun Simulator

Something that looks like a gun, but when the trigger is pulled the simulator emits a short laser pulse. A camera then looks at the target and evaluates where the laser hit. Or you can evaluate yourself if you hit or not. There are several cellphone apps that do this scoring for you. 

Main features:

• Gun Features:
  • Adjustable two-stage trigger pull
  • Rear sights adjustable for elevation and windage
  • Loading lever required to be opened between pulls
• Easily available parts:
  • 18650 battery
  • Standard 12mm laser module. I used a 5mw red laser.
  • KW-12 switches  for trigger and loading lever
  • Lolin32-lite as a microcontroller/charge controller
  • m3x10, m3x20, m3 nylock and m2x10 are the only required hardware
• Highly modular, to allow incremental design:
  • Front/rear sights bolt on
  • Trigger/loading lever mechanism is removable
  • Electronics bay is large and available in non-microcontroller specific variant.
• Easily printable
  • No tight tolerances aside from the trigger/loading lever pivots, which can be drilled out/sanded as needed.
  • Fits on a 256x256 bed (just)
  • All printable without supports (though there is one rather long bridge)

I'd like to spend more time refining the design, but other projects call! All the source files are available on github: https://github.com/sdfgeoff/LaserRunPistol

I haven't put together an assembly guide, but here's a picture of the most complex assembly - the trigger plate:

And the model “pistol-complete.stl” shows how everything goes together.