The day before we were heading to DragonCon 2015, I decided to build a quick blaster to carry around. Nothing like a last minute project…

The 3D Printed Parts
All of the 3D printed parts were designed in OpenSCAD. Then sent through Slic3r and finally to the printer. All told, it was probably about 9-10 hours of printing (including “tweak” reprints).

The Electronics
I used an AdaFruit Trinket as the LED controller and a perf board to wire up the switching circuit for three channels; an “indicator” LED on the back of the blaster, a couple of LEDs which illuminated the “top” of the blaster and the LED to simulate the muzzle blast.

Blaster open showing Trinket and switching board.

The Code
For the LED effects, I reused the same LED PWM code that has been used in my previous projects. It’s basically just a timer running at 10kHz, with 100 frames of 100Hz LED intensity PWM for each channel. The LED intensity values are controlled by a single function and those intensity values range from zero(off) to 100(full). Simple. Then it’s just a matter of running a “ready” sequence while waiting for the trigger to be pulled, and then the “blast” sequence is initiated.

Assembly
Once the parts were ready and the coding complete, the assemble was a snap, just a little super glue to attach the barrel and handgrip to the body and to glue the barrel end to the cap. The rest of the components are simply press-fit together, which allows me to disassemble it, if needed. A 9v battery fits snugly in the handgrip to power the system.

Below is a picture showing all of the blaster components.

The Result
Below is a picture of the completed blaster, ready for the con! It’s a pretty basic blaster, and there are definitely plenty more tweaks that could be done, more details that could be added, etc.
Most light/sound props all have the same basic electronics needs, so I may actually design a proper electronics pack in the near future.  Blaster v1.1, maybe!