Help I'm addicted to Lilypad LEDs!

This is a sneak peak at my latest work (in progress).

I am waiting for more supplies to arrive from Sparkfun, as I've become quite excited about Lilypad LEDs.  I had no idea that this was going to become such an expensive hobby!

In the process of creating this book cover, which is currently being powered by a 9V battery (that is NOT small enough to be hidden away in the book's innards), I have come up with a couple of ideas for solutions, which I'm not yet sure will work.

Here's a look at the inside of the cover, 

and the offending power supply.

My Plan:

1.  Substitute one or more of the LEDs for a Lilypad slide switch to reduce the amount of energy needed to power the circuit, and bringing the total number of LEDs down to 10.

2.  Substitute the 9V battery for a Lilypad power supply that allows a AAA battery to power up 10 X LEDs  (up to 220 mAh).  (Update:  the power supply is also too thick!)

3.  Cut a hole in the book block that is large enough to house the power supply before assembling it.

If you have another suggestion for a way to power these LEDs with a small and tidy energy source, please let me know!

NGSS Framework Practices Addressed

1.  Asking questions (for science) and defining problems (for engineering)

2.  Developing and using models

3.  Planning and carrying out investigations

4.  Analyzing and interpreting data

5.  Using mathematics and computation thinking

6.  Constructing explanations (for science) and designing solutions (for engineering)

8.  Obtaining, evaluating, and communicating information