Has anyone ever seen a tool for unscrewing the torx screw inside a Bohème cap?

[Kismet]

Oops! on the ebay mistake... missed that they were Hex even though I did a "Torx" search.

EUMRO does make an E4 size in their 1/4" Square Drive Sockets. Not sure it will work due to its shape/size for your pen opening but... they do taper down. Check them out here: https://eumro.co.uk/apex-square-driv...ets-eumro.aspx

Here: https://eumro.co.uk/apex-1-4-square-...all-eumro.aspx
or Here: https://eumro.co.uk/apex-1-4-square-...ews-eumro.aspx

I also located this set, which has a flexible shaft that may be useful. It's a bit pricey and the smallest is E4 so if you need something smaller, it won't help, but even so, worth a look: https://www.amazon.co.uk/CTA-Tools-8.../dp/B07CZRRN51

Here is the manufacturer's website link: https://www.ctatools.com/index.php?r...roduct_id=1746

Best of luck! Wish I owned a Bohème pen to measure... challenging with a tapered opening to figure out what size/shape will work.