After opting to use the arduino uno prototype board for this project, I started thinking about case design.  I needed something as small and as ligh as possible which could easily be fixed onto the inside of a jumper.  I decided upon this thin blue plastic which could easily be bent on a strip heater.  I measured and then bent two case sections, one wider than the other so they would slot together.  This design also meant access to the various cable was easily achievable. I drilled a hole in the top for the potentiometer to sit and then set to work designing a system that could secure it to the jumper.  I settled for velcro as the method of attachment because it is strong and easily glued into place.  I also attached a piece of elastic with velcro tabs at each end which secure the two halves of the case together.  This design appears to work well.
After having glued each LED to a ping pong ball the night before I set about designing the mounting system for this.  I only just had enough ping pong balls so I had to get it right first time; a situation I would not put myself in again.  I had already decided not to mount the LED's in the balls as this would require cutting large holes, which could easily lead to ruined ping pongs.  Having the balls mounted on the outside, meant that I had to secure the wires in some way so the weight of the ball wasn't on the tiny LED pads.  I decided upon poking holes and using them as strain holes which would also mean I could use the wires to mount the balls to the jumper.  As you can see from the picture each wire goes in one hole, out another, doubles back and wraps around itself.  I soldered these twists for strength and the  routed each of the 4 wires.  I was very pleased with this method of attachment as securing the balls to the jumper very easy and reliable, preventing and shorts from occurring.  After constructing each one I carefully hooked up, and tested them.  I lost 1 ball in the process by accidentally connecting the GND wire to VIN on the arduino which is the voltage rail.  I was down to 8 balls.

Next I set about work on the jumper.  I used little pieces of wire, poked through the jumper and twisted together to hold the tinsel outline of a Christmas tree in place.  Later I soldered these twists and then trimmed the down.  I also tied some mini gold disco balls to each point for decorative measure.  Finnally I pushed the ping pong balls wire connections through and twisted them together to hold them in place.

 Well aware of the sensitive polarity of these LEDs I decided that a labeling system would be required.  After having secured all the balls in place I painstakingly checked all the connections and labelled them with little flags that I had printed off.  This was very effective and is definitely a technique I will be using again.  It meant that when I turned the jumper inside out, I was able to connect everything without having to turn it over and check connections.

After attaching the balls in place I realized that the arduino still needed a velcro attachment point on the jumper, so I decided to sew in a velcro path before I went any further.  It was hard enough with the ping pong balls attached anyway!

 After this I proceeded to make all the connections between balls.  I used a combination of conductive thread and solid core wire.  This was my first experience of conductive thread so I did a little bit of research to refine my technique.  I ended up making loops of wire in the connection wires from the ping pong balls.  This allowed me to tie the thread to each connection and then sew between connection points.  I also used some bare conductive paint to ensure a good connection between thread and wire.  In some cases the balls connections wires were long enough to solder together so that was easy.  After about two hours it was done.

After hooking up the alligator clips for a test run, I triple checked everything, in the full knowledge that one connection would blow all the LEDs up.  I loaded some test code onto the arduino and plugged it in.  After the most tense couple of seconds in my life, the LEDs lit up!  This was a relieving sight.  That night I woke up with a very bad headache which I put down to the stress of making these connections.  But it was worth it, the next day I got in from school and immediately started tidying the insides up; after securing a piece of cloth to cover the connections and spiky wires I sat down and started to write some animations.  This was by far the easiest bit.

With little time I was unable to integrate the microphone into my code but this is something I hope to do in the future.  All in all I feel this has been  a very successful project, and I hope to do more like it in the future.  i have also learnt a lot which, I will no doubt be able to apply in future projects.