Backpack Laser Rifle

It all started from a toy “Xploderz” watergun, and a glass vase I found at the dollar store. The watergun wasn’t any good, but I thought the design looked pretty cool. I thought it would look cooler if the tube was actually glass and included a red Cold Cathode Florescent Lamp (CCFL) used for computer modding.

To mount the CCFL into the tube, I 3D printed a part that’ll snap onto the open end of the vase. It took a few generations to find that right “fit” that allowed the cap to snap on the glass lip, and around the CCFL.

Next step was to molest the watergun with a dremel, and remove any plastic I didn’t want. The CCFL and the Water gun was a little longer than one glass vase, plus I dropped & cracked the first vase that I found. So I had to go back to the dollar store and buy more, I got a few extras just in case. Found that two together were enough to have the tube hang out the back long enough for a stock to hold on the back end.  To support the glass tube, I fitted a copper pipe into the assembly which adds a nice steampunk flair.

The electronics in pieced together are fairly simple, I used lamp wire to connect a 12v SLA battery to the CCFL transformer. I have a momentary push switch that I fit in place of a trigger. I also have a 12v-5v step down circut ripped out of an old USB car charger to power a laser diode. There’s a better way, but this was still a prototyping stage, and I wanted to go modular for now.

Glued a cone to the tip, it hid the large hole in the front and focuses the beam and provides a place to mount the laser diode. Used krylon plastic primer on the water gun shell, taped off the handles, then used a metallic spray on the rest of the gun.

Now to start fitting the parts back together. To bring the power to the gun, I fed the wires through a metal cable sheath. A simple hose clamp kept the sheath from pulling through the hole. I had a couple problems, need to cover the butt in a way that supports the glass tube and the copper pipe. I used a small section of ABS pipe, and dremeled out a hole for the copper pipe. I also needed to support the front of the glass tube as it would sag down and looked funny. I found that a spray painted square of cardboard worked. I took the gun like this, with the battery in a leather pouch to Phoenix Comic Con Fan Fest 2015.

A good powerful laser generates a lot of heat, so you need a way to cool it down. There’s no room on the rifle itself for cooling, it would be too bulky and heavy to add a pump and radiator on the gun itself. So I set on building a backpack to hold the radiator, fan, and battery. I found some nice looking boards at my local hardware shop, planed and sanded them down to a nice and smooth finish, then fitted them around the components that I wanted inside the backpack. I also wanted a little more room above the battery for extra wires and circuitry. The radiator is an automotive heater core, chose it for it’s size and all metal construction. If I were to do this again, I would specifically choose a different type of wood what I picked up was too soft and was designed as fence board. Next time: plywood, or hardwood boards.

Used plywood for the back and front of the backpack, cut a hole on the front for the fan and radiator tubes. I finished it all up with Danish Oil to give a nice dark wood. I then cut holes in the side to allow air to pass in from behind the radiator, and to feed the wires. Added a hole, and routed around the back to mount a power switch to the face of the backpack. I also braized on a small copper pipe into the larger inlet of the radiator, this allows me to use the same size water hose for the in and out.

Added cabinet hinges and latches to secure the door, also added a copper knob to polish it off. Added a few LED’s into the battery compartment to add a “green” glow.

To finish the laser rifle off, I used water hose to connect the radiator to the side of the laser rifle. I textured the water hose with plastidip, then wrapped the hose in canvas. I stapled a sheet of canvas on the inside of the 3 openings in front of the battery compartment, so you can see a green glow but not directly look at the power source. I replaced the ABS butt with a block of wood that I hand shaped and fitted around the copper pipe and glass vase. I then made leather straps to support the glass tube, and cover the 3D printed parts suspending the CCFL lamp. Because my modifications removed some of the plastic supporting the top section of the gun, I used metal straps to secure the gun together. I also added a leather belt to the back of the backpack, and a leather strap around the laser so I can sling it around my shoulder. I wore the gun like this to Wild Wild West con 2016. The backpack was way too heavy, and the leather straps were too thin and weren’t supporting the weight well. The screws I used to secure the belt on were also getting loose, though a drop of boltlocker fixed that.

To improve the comfort of the gun, I created a much broader leather strap that crosses in front, and added a loop to the side of the backpack to clip the rifle too. Now I don’t need to have the strap, though that option is still there. Wore it this way to Phoenix Comic Con 2016.

The cone fell off at the convention, and I never did finish mounting the LED diode on the front of the gun. I decided I like the look without the cone, it’s more menacing so I just refinished the front of the gun. I’m considering the project done at this point, but there are a few changes I would like to incorporate if I find the time. I want to move the power switch to the blaster handle, so I don’t need to reach behind myself. I would also replace the SLA battery with a smaller lithium cell.