David, thanks, I think....

Actually, the real sensing element is far smaller than the housing. The real sensor can be glued to the crankcase and reduce the footprint substantially. But it's too much fussing and not really necessary......

Yes that was the original device I came up with also and in reality, if it surrounded only the sensor element, would be far smaller. I spoke to Todd Syssa about making a few of them but that never materialized.

I've considered getting a combo lathe set-up but that's not in the cards right now.....I don't have easy access to a machining center so I dropped it for something I could build at home with hand tools. Indeed my sub-ring was "skeletonised". Weight would have been around 7 grams or so, if built from ally. I haven't completely discarded the idea of making a mold for plastic parts. It's on a back burner

BTW- the nose ring design I show is not a prototype. It is a fully functional device that has seen service in several airplanes and 6 different engines in 3 years of flying, (lessee, 2 SAP180's. a DLE55, a Mintor 38, a ZDZ40, the current OS33 and will soon see service on the PTE36) some 30 gallons of gasoline and some 150 hours of service. It works great! Try it......