Hey Guys, first build here and I could use some help with the internals of my saber.

The design as it stands now:
external.jpginternal.jpg

Cant afford to add sound now but may do further down the track, I'm planning on getting purple blade colour using a custom R/G/B Tri-Cree using the method detailed here: https://www.youtube.com/watch?v=JbHpTKiLfA4 but I'm a bit confused about the power system. Li-ion seems the best option but I live outside of the US so would have to purchase it locally, what would the advantages be in going Li-ion over 4AAA and vice-versa?
Also, would I be able to fit the electronics I need inside the 5" double female extension that I am using for the main body?

Thanks for your help, excited to start building!