Decisions that are settled:
1 - There needs to be a 4" copper grip min which will conceal the electronics. It’ll be acid etched (not sure what pattern). That’s about the width of my grip and any excess covering of the blade is a dash of fail.
2 - Although I usually don’t prototype, there is so much risk of damage just from swinging that physical stress testing is in order. Each piece will be built with scrap blade tube before the final, and it will have to swing well empty + the battery cells.
Uh…yeah not sure about the rest but I tried 2 layouts so far.
Layout 1:
Here the end piece below the grip would be primary access. There’s a 4ohm 3watt 20mm speaker inside the upper housing that accompanies the heatsink that will be used to house the connecting cord/chain.
Like this:
The proffie would sit centered in a switch ring (from TCSS). There’s not a lot of blade depth, which is not good and may not endure the swing stress. BUT, I can do a “blade chassis” and have the copper piece acting mostly as a shield. That messes up the switch and I’d have to put it on a spring, so I could compress it and remove the copper to get acess to the internals. The recharge port would live inside there some where. Not sure.
I did a similar set up for my brother in law. I was specifically instructed by my nephew to make him a saber “not as cool as mine”, so it’s a baselit CFX 
in a Flyte hilt that I painted and weathered for a Boba Fett look. The blade is an early photonic green dueling blade I repurposed. This gives the shine through one color, and the blade another from the same tri-cree:
But, I dunno. As Moe Howard would say, it’s my idea but I don’t think much of it.
So here’s layout 2:
This doesn’t have the passthrough blade chassis, which increases the internal diameter. I can stack the battery and the board and use an external recharge port, and a 24 mm speaker. The rcp can sit opposite the single tac switch, which is part of the tail end of the chuck. They can be fixed because I get a 1 inch blade depth back and can open the core from the top: There will be 4-40 button head “rivets” that go into the blade tube itself, which could be removed for access to the internals. No set screws that use pressure.
Here’s how I did the switch ring in the lower blade:
It’s on the outside for a near perfect fit to th ID of the copper. It’ll need a little sanding once they’re bonded to get it just so.
I’m using enchaced amber blade tubes to summon the golden dragon vibe, so that’s why the blade tips look like that.
Next I’ll figure of these two build styles to try as a full swingin’ prototype. These are quite dangerous compared to the usual saber chucks with the heavy hilt at the top. Not for the kids.
Feedback welcome, and thanks for looking!