A Bic lighter cover for an engineer I know.
https://www.wolframalpha.com/input?i=given+name+Greg
The lighter only goes in until it hits a ridge near the bottom so as to leave a space to hold a few pills under the lighter. I call it: Un Bic avec sous-sol
The second file GregBicRingHoles.stl has two holes at the bottom for metal split ring or a piece of thin cord for a lanyard loop.