I thought I might as well share being a member. I've helped a few people build these already and I could see a squonker being built out of these too but I haven't done it yet.
This build all starts with a power bank and ends up as a no tools needed Dual SX350 mod.
You'll need one of these first.
https://www.fasttech.com/products/1381305Some of the plastic has to be cut away so the SX350 will fit. I do this the opposite side of the button.

The bottom under the sticker is where a solder joint is found to take the power bank apart. The top is glued in place and a exacto knife can be used in the centers and just outside the button to remove the plastic top. I removed some plastic to seat the eventual metal in the top which is a tight press fit backed up with some JB weld.

I used hot glue on the edges of the circuit board to hold it in place first and than widdled the hole for charging/data USB.

A USB test

I ended up having to bolster the springs some, they were getting warm real quick at 50 watts. This one looks like crap but since I've clean up my act in this department.

I used some liquid tape for some extra protection of the boards.

And in the end it all works out to make a fairly compact dual 18650 mod I don't need tools to change batteries in.

I modified a FDVs Stainless 510 to be spring loaded, no connection issues and none of the goofy adjusting.
These kind of remind my of Storm Troopers so I'm calling them Steam Troopers.