LED Plasma Weapon Tutorial

This is my tutorial for placing LEDs inside plasma weapons. The photos show this technique applied to a Hellblaster Primaris Marine with plasma incinerator, but it can equally be applied to regular plasma guns, or indeed any other model that you feel would benefit from glowing power cells.

I strongly recommend reading through the entire tutorial before starting work, just to make sure you have the necessary skills and tools required and that you’re not going to run into an unexpected barrier halfway through.

I have a separate tutorial about designing LED circuits, basic LED solderingresin casting and LED eye lenses. This tutorial assumes you’ve either read these, or are familiar with the techniques discussed, especially the eye lens tutorial, which is a starting point this tutorial builds from.

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1. First, complete step 1 – 12 of my LED eye lens tutorial. This assumes you going to have LED eye lenses and LED plasma weapons on the same model. If not, and you only want a LED plasma weapons, you only need to complete steps 1 – 10 of that tutorial.

2. Drill out the inside of the plasma weapon, starting from barrel. I recommend starting from the barrel as that means the hole will definitely be in the right place. If you start from the other end then it might not be.

The objective of drilling out the plasma weapon is two-fold; firstly it allows the LED light to shine out of the barrel, and secondly if you can get the LED inside the body of the weapon then you can make the coils and vents glow (skip to the completed image at the bottom of this page if you’re not sure why I mean). Obviously if you want the coils to glow then you need to be working in a thin material like resin – the coil glow effect will not work in metal or plastic!

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3. Once you have drilled the hole, dry fit the LED in the opposite end to the barrel, underneath the power coils. If you drilled a small hole in the barrel, you may find yourself having to partially re-drill a bigger hole under the coils to make sure the LED fits. When you insert the LED sure it is pointing towards the barrel, so light will be visible if anyone looks into the muzzle of the weapon.

Remember you can hold a coin cell battery between the legs of the LED at this point to get an idea of what the glow effect will look like. If you find it is not as bright as you’d hoped then you can use a circular file to carefully widen the hole. Unfortunately, if you breach the coil at this step then you can’t repair it without ruining the effect, so go carefully! If you do make any mistakes that break the surface of the coil then I’m afraid you’ll need another plasma gun and will have to start again…

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4. If you’re following this guide through literally step-by-step then you should currently have a battery holder inserted in a base with two wires coming off it. As you have two LEDs on this model (assuming you’re doing the eye lenses too) then you need two more wires to run up through the legs.

It is of course perfectly possible to just have a two wires passing up through the legs, and to make the connections in the torso, but I have found through experience that this is more fiddly and is also more likely to result in an unintended short circuit later on when you assemble the rest of the model. The extra wires can be connected to the same points – the battery terminal and the switch – as the existing wires, since you are making a “parallel” circuit.

Remember that if you’re using two different types or colours LED then one of them will probably need a resistor in the circuit to balance the current draw – different LEDs will have different current draws. If you’re not sure how to determine what type of resistor you need then that is covered in my designing LED circuits tutorial. If you look carefully at the picture below then you can see the resistor is simply connected in “series” between one of the lengths of wire and the switch, giving that branch of the parallel circuit a different resistance to the other and helping to balance the current draw.

If you are duplicating my model exactly, then the red LED for the eyes is a TruOpto OSHR7331A-KL 1.8mm Red LED, the pink LED for the plasma is a TruOpto OSPK7331A-KL 1.8mm Pink LED, and the resistor – connected in series with the red LED – is a 100Ω resistor (any brand will do). Whichever LEDs you are using, make sure they are compatible with the voltage of the battery – 3V in the case of the coin cells used here.

Designer’s Notes: Why Pink For Plasma?

There are a number of reasons I chose pink as my colour for plasma. Firstly, the range of miniature LEDs I use only has a finite selection of colours available, and I’d used a lot of the other colours already. Secondly, I’ve used argon plasma in semiconductor fabrication processes in a previous job, and that was pink, so I tend to associate pink with plasma. Thirdly, it’s pretty eye-catching, and tends to stand out among the other LEDs.

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5. Check that the hole you have drilled in the model’s leg is wide enough to accommodate all four wires, and feed them through. It can be useful to mark which wire is which before you feed them through, so you know which wires are connected to the positive side of the battery, which are connected to the negative side, and which is the one connected to the resistor (if you are using one). You can mark the ends of the insulation with a tiny dot of paint, or similar, as a reminder.

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6. Now you need to figure out where the wires are going to exit the torso of your model and enter the plasma weapon. Dry fit the torso and the arm that holds the handle of the plasma weapon, using blu tack to temporarily hold the components in in place if necessary.

You’ll notice in the image below that the front half of the plasma weapon is missing. That’s because I had already removed it and recast it in resin for this project.

Once the components are temporarily held in place you should find a point on the torso where the butt of the plasma gun touches the miniature’s chest. Move the plasma gun out of the way, mark this point of contact in some way and then proceed to the next step.

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7. I find the easiest way to pass the wires into the gun is simply to drill a hole in the torso at the point that you marked in the previous step, where the gun is held closest to the body of the miniature. Don’t worry, once the model is assembled this will not be visible. Pass the two wires that are going to connect to the LED in the plasma weapon through the hole. If you are following the guide exactly using the same LEDs as I did, then make sure this is the pair of wires without the resistor in series.

An alternative to drilling through the torso is of course to carefully drill along the arm holding the grip of the weapon. This is more time consuming, but might be your only choice if the weapon is held away from the body, such as in a plasma pistol, for example.

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8. Now you will need to drill a hole through the stock of the plasma gun, so that the wires from the torso hole can enter the stock, then run along the length of the weapon to where the resin barrel section will attach. As always, don’t worry if you drill anything you shouldn’t, as any damage can be filled in with modelling putty later.

Once you have passed the wires through, solder your plasma gun LED into place. Don’t forget to check the polarity! Once the LED is soldered in place, fit the resin barrel of the plasma rifle over the LED and glue it into place with a tiny dab of superglue. Keep the superglue away from the coil section of the plasma gun.

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9. Next, pull through any slack on the wires until you have a coil of wire under the feet of the miniature. We will conceal this later on. Now glue the left arm of the miniature into place, making sure the barrel of the plasma weapon is held straight and in line with the stock.

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10. Now is a good time to check that the plasma gun LED is working properly before you proceed!

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11. Next complete steps 13 – 17 of the eye lens tutorial to connect the helmet. When you get to step 17 and are filling in gaps with modelling putty, don’t forget to fill in any gaps between the stock of the plasma gun and the barrel.

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12. And there we have it, one LED lit miniature! We’re almost there now. The next step is to undercoat the miniature for painting.

During spray undercoating, make sure you cover the helmet eye lenses, the plasma coils, plasma cooling vents (around the muzzle), barrel and the top of the switch with blu tack (or similar) so that they don’t get spray paint on them! If you are spraying from underneath then you will also want to cover the battery itself during the spraying process.

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13. Now apply paint, avoiding the eye lenses and any parts of the plasma weapon that you want to glow, and that’s it! If you find the light is leaking through in any area it shouldn’t, especially from the helmet, then an extra coat of paint will normally sort that out. I hope this tutorial was helpful!

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