Debating whether to just trim down the star (think it’s 18mm to fit), and have a resistor lead tucked underneath and around be the (+) contact, or have a press-fit perfboard under the star for a discrete contact board.
I got as far as trimming a star to fit (WW “bead”, Amazon.com ), measured the crap out of all the internal dimensions and the cell itself (Li cell and 3V converter board, https://www.amazon.com/dp/B0874QQ2C6/ ) so I don’t have to worry about a full 4.2V down to 3.0V supply (ie, cook when fresh, almost nothing when spent).
A CR123 with a built in charger and voltage regulator… Now why didn’t I think of that before? I was concerned about replacing that 1 ohm smd resistor because I may have to use a RC123 at 3.7v.