This is a replacement for Suzuki part 44348-87420-000.
On my GSF 600 Bandit (2001) this gasket was leaking. So I designed a replacement one which fits well and does not leak (24h from now).
Hint: to make it fit well, apply some grease to it ! It will stay in place when you will be mounting the tap on the tank.
I printed it using cheap chinese flexible filament (TPU, brand "jurui " found on aliexpress). This is supposed to not dissolve or be degraded by gazoline. By the way I ordered a repair kit to rebuild the whole tap: I just hope this printed gasket will live enough ;)
Edit: This gasket did his job for 2 weeks (the time for the brand new gasket to arrive). When I replaced it, it was not degraded: I put it in a jar with some gazoline. One year after, the gasket is still ok: so I think it would have last a long time.