One of the major open questions about the current design is the power source. Ideally the device should be battery powered, so whatever battery I select should be able to run both the sound and the light strips for at least an hour. 

Today I tested some 18650 lithium-ion cells from an old laptop battery. The two cells were connected in parallel. After charging the cells, I discharged them by connecting one of the light strips with all of the pixels set to red at full intensity. Since the LEDs were not running at their intended 5 volts, but only at around 3.7 volts, they were less bright, but also consumed significantly less power. 

The batteries started out at around 4 volts, with the LEDs drawing a total of about 1 amp. After about 3.5 hours, the voltage had dropped to about 3.5 volts and the current had dropped to around 650mA. I calculated the total capacity of the two batteries as around 2.8 Ah. 

Since I was only testing the batteries with one of the LED strips, I would expect them to last around 1.5 hours with two strips and the amplifier. Furthermore, the batteries were quite old and only have 2800mAh combined, so a single new 3000mAh battery would probably suffice to power the lightsaber for a good amount of time. This also helps keep the cost down, since 18650 batteries are quite expensive.