Let’s Talk About Cardboard Core Props – Plasma Defender (part 2)

This post originally appeared on the GlitzParty Cosplay tumblr in 2012. It has been preserved for posterity to aid other cosplayers here!

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now, we left off last time with the centre piece cut out of the cardboard with channels going through it for the electronics, when they arrived.  in this photo we can see where i began to built up the second layer, complete with inlays to flesh out where the detailing would be.

at this point, you want to plan the depth of everything on your prop.  how thick does the thickest part need to be?  are there any inlaid pieces? cutouts?  how much cardboard is needed to keep everything the proper shape?

it’s worth mentioning at this point that the inlays are pre-emptive for our later work, since they will be filled in and covered up in the coming steps.  they are only cut out so that when we inlay as necessary, we don’t hit cardboard as easily.  just making space for later carving, essentially.

at this point, we’re more or less ready to start our electrical component.  opinions vary on where is the best/cheapest place to get parts and LEDs. i personally used plasmaLED.com for my LEDs, since they come with resistors already attached and everything sealed to the point of being waterproof.  for everything else, i used allelectronics.com.  both shipped fast, were packed well and everything i ordered worked fine.

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you can see the LED here with the resistor already soldered to the wire and shrink-tubed shut.  this particular LED was going to be for the main barrel of the gun, so i cut out a disc of cardboard to hold it in the centre were the hole would be and glued it into place.

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the inside of the PVC cap was sprayed silver to try and reflect some light, no word on whether or not that helped, haha!  i couldn’t resist hooking the LEDs up to the battery at this point and testing.  red wire is your positive current, black is your negative current, though when using the 9v caps from allelectronics.com, the wires were already properly colour-coded for an easy hook-up.

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from here i apparently didn’t think it prudent to take photos, since it was pretty haphazard for a while.  in short, i wired 5 LEDs in parallel with the 9v and a simple click switch.


image courtesy of google, this is a simple diagram of a parallel circuit.  essentially, what is happening when you wire things in parallel is that you are sharing the current equally between the two lights, versus when you wire in series and all the lights share a single current.  wiring in parallel also means that if one of my LEDs were to blow, the others would remain lit, as the circuit would not be broken to the other LEDs.

in textual format, i took the LEDs and twisted together all of the red wires to form a single wire, same for the black.  the positive wires were soldered directly onto the positive wire from the 9v connector.  the negative twist was soldered onto one end of the switch and the other end was in turn soldered to the negative wire of the 9v connector.

the next step was chronicled in this video where you can almost see where i made a wooden battery case.  all in all, it turned out serviceably, though it was a really tight fit with all of the wires, 9v, connector and switch.  

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the battery case has a sliding bottom that opens it up so that the 9v can be replaced as needed.  conveniently, the design for the plasma defender has nubs on either side of the little box on the bottom that my switch could pose as.  the other will be a thin dowel to match.

this is getting really long, so i’ll cut it off here.  questions encouraged, tune in for part 3 in the coming weeks!

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