Once I finish my Graflex I'm already lining up my next saber and I'm planning a step up on this design approach. I'm planning to do a new Crossguard 2.0 build with a Proffieboard (my original was with the Prizm but I have some things I want to do differently now that I've got my feet wet) and after messing around and testing I'm going to use two 21700s and a DPDT switch (ON / OFF / ON) with the Crossguard. It's going to be tight fit but I roughed the main parts in so I think I can make it work. Since the Crossguard doesn't really have a great location for a recharge port I'll be using JST connectors like I did on my first build so I can take the batteries out and then recharge them outside the saber. Here's the wiring diagram for the battery set up, this switch has 3 positions, first position will use Battery 1, middle position is OFF and third position is Battery 2, this eliminates the need for a kill key and let's me swap power supplies even better. I've done the rough fittings for everything, I have three potential locations for the switch but I need to finish my Graflex and save up some money for the chassis and parts to see the best fit based on everything, so it'll be a little while before I tackle it, but anyone interested here's another option for this approach that can eliminate the need for the kill key/recharge port.