In this build I will show you how I made my Iron Man Arc Reactor chest piece designed for wearing under a shirt.
For this build you will need:

Parts:
- An old broken speaker
- A jar lid
- A number of LED's depending on how many holes your speaker backing has (I had 14)
- Insulated wire
- Some form of insulation (Insulation tape, heat shrink tubing)
- 2x 100 Ohm resistors (I recommend 1/2 Watt rated
- Solder
- Wax paper
- 9V / 6AA battries
- Clear adhesive glue(Glue gun or clear adhesive)
- Chest belt or a waist belt that can fit around your chest

Tools:
- Soldering Iron
- Glue Gun
- Duct Tape
- Drill
- Vice

Step 1: Making the Base

To make the base I used an old speaker and removed the fabric/membrane to allow it to be a stencil for the lights to shine through.
I used a peanut butter jar lid to mount the LED's on which happend to fit perfectly in the groove of the speaker.

Step 2: Mounting the LED's

Firstly I placed black Duct tape over the inside of the jar lid to prevent it from shorting out any connections with the LED's

I then placed the speaker backing over the jar lid and used a spring loaded punch (A normal punch will work fine too) to make dents in the lid where I wanted LED's to be.

To mount the LED's I simply measured the diameter of the LED and found it to be 3MM and got a 3MM bit for the drill.
After I was happy with the placement I simply placed the lid in a vice and drilled the holes in the dents. I made a minor mistake here by not placing some insulation such as duct tape on the inside of the holes as this created momentary short circuits sometimes which made the lights go off and on, but after buckling the lid a but, it didn't short. I would recommend you insert some duct tape or insulation tape on the rim of the inside of the holes made in the lid.

Step 3: Removing the Magnet From Your Speaker

This part was tough but I eventually got it right

As you can see from the picture, there are angle grinder markings on the on the metal backing. . . Basically I tried and tried with the angle grinder but it was much too hard and much too thick. So eventually I popped it in a vice and bent it and flexed it a bit and it just popped right out. . . I felt like a fool because it was actually press fitted . . . and well, I didn't need to go overkill it with an angle grinder, but oh well. It works.

Step 4: Wiring Up the Circuit

As you can see from the circuit diagram I made in the very professional electronics design software called MSPaint. The LED's are all wired up in parallel with a 100 Ohm Resistor in series with this. I recommend this resistor atleast be a 1/2 Watt rated 100 Ohm resistor as it may get quite warm and you dont want it to burn up. after all the glue for the LED's has dried, place the jar lid in a vice and bend all the positive (+) leads outwards and all the negative leads around the inside as seen in the pictures. (For LED's the longer leg is the positive lead and the shorter lead is the negative lead, you can also tell where the negative lead is by a small grooved out piece of the LED being inline with it)

Solder small pieces of wire between all the anodes(+) and simply solder the negative leads of all the cathodes(-) together. you can make a completely closed loop like I did in the picture for the anodes (Blue pieces of wire) or you can just go around the circle until the last led like I did with the standard metal legs of the LED's (I was getting tired and it worked so it didnt matter to me)

Next is to insulate the whole thing.
There are many ways of insulating this (Luckly the jar lid is painted so I didnt need to insulate the whole lide with tape)
So all I did to insulate it was use hot glue all along the tracks to firstly mount it and secondly, insulate it. Remember to leave 2 points one for the positive and the other for the negative uninsulated so you can apply power! I recommend using the one point of the resistor as the negative and a LED near the resistor as the positive.

Step 5: Inserting Centre Lights

This is optional: To do this, do the same as mentioned in the previous steps

Make 5 holes in the centre with the same width as the LED's you are using.
Glue them in place.
After the glue has dried, begin following the same circuit as mentioned in the previous step just with less LED's but same resistor.

solder the positive lead of this circuit to the positive lead of the previous circuit, and solder the negative lead of this circuit to the negative lead of the previous circuit so the 2 circuits will run in parallel with eachother (Refer to the picture)

After you have tested it and it works fine, be sure to glue it all up and insulate everything.

Step 6: Profiling Your Stencil

Now that everything is working electrically, lets get more into aesthetics.

I used something know as Tin Snibs to cut the speaker backing into a circular shape, however I do not know if this is a very readily available tool so you could use a dremel or even an angle grider to cut this, whatever works for you.

Step 7: Making the Filter

Now to make the light less vivid and more opaque.

I used baking tray paper which is basically wax paper.

I first cut it into a circle and simply placed it inside to see what it looks like. It was alright but I felt the centre wasn't working how I wanted it to so I cut out the centre of the wax paper and placed it in the indentation of the speaker where the magnet was which worked wonders for the effect.

Step 8: Mounting and Using

To mount the arc reactor I started by:
Cutting out a plastic lid to be the same size as the device and hot glued it to the back of the reactor. I did this to prevent any breakage of the circuitry and to have a clean, level surface for glueing the device.

I glued it to a chest belt using fabric glue but a normal waist belt can work too and that was my origonal choice but I found this which worked way better.

for powering it I used a 9V battery but it can just as easily run on 4 AA batteries = +-6V. A problem I did have was that the 9V battery was used up very quickly so in the future I will use 6AA batteries to make 9V but with a lot more Ah (Amp hours) giving it longer life.

Its up to you where you want the battery, I ran a cable down the inside of my shirt to my back pocket and kept it all in there. you could also mount it on the belt itself but it may show up if you are wearing a tight fitting top.