I had heard of gas cylinders in office chairs, but not coins. I found this paper that mentions both: https://www.emcesd.com/pdf/uesd99-w.pdf https://www.emcesd.

I had heard of gas cylinders in office chairs, but not coins. I found this paper that mentions both: https://www.emcesd.com/pdf/uesd99-w.pdf https://www.emcesd.com/pdf/uesd99-w.pdf