Nik
I will help to determine if Otter can assist & there response suggests that one of there current designs could be adapted to suit, I am certainly not going to get into the filler cap saga, I have enough to do with the Weller engines & the tens of thousands I have spent on that project.
As with the PVT stub axles I will ask the Club to take it over & invest as I am sure the requirement for these small but important parts will be required to keep the valuable AC cars working as intended, at the moment I do not anticipate major costs but what is important is the support of the owners of these cars to make some commitments.
My interest is in the PVT AC cars which do not have this sophistication I am pleased to say, as with Stub Axles I will initiate then expect the other Club members & the Club to take over!!