This interests me a lot. I am currently using a pair of Nano Biscotte inside some ultrasabers. So some questions. Why do we need the 5v Booster? Can a Teensy not work on 3.7v?
Which is the more economical version to build? I already have a speaker, a 18650, a bag of tactile buttons, and an RGBW led star.
Originally I added the booster because of paranoia; I wasn't sure that the battery voltage would be enough.
However, it turns out you really want to drive the amplifier at 5 volts to get the maximum volume out of it, so having a booster turns out to be a good thing. The booster also isolates the cpu and audio circuitry from battery ripple, which can otherwise cause some problems.
As for the economics:
NB costs $67 (at TCSS)
teensysaber V1 costs something like $20 for the teensy, $20 for the prop shield, $8 for the SD card, $15 for the booster + $5 for the FETs = $68, but is much larger, doesn't fit most hilts and requires a lot more work to put together.
teensysaber V2 costs sometning like $60, plus $20 for the teensy = $80, so it's a little more expensive, but fits in most hilts. I don't have any teensysaber V2 for sale right now, I should have more in a couple of weeks though.
I hope to get the price of teensysabers down in the future, but that is dependent on volume of sales and will take a while.