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Replying to @MakeAugusta

I don’t think that leaves room for the pen! The space pen refill is 9 cm long and has to sit centered in the body; figure another 5-6 for the gadget and you’re at 14-15 cm — ideal pen range. Also diameter: I’d like to keep it under 14mm for writing comfort, and a 18650 is chonky.

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