I’ve been messing around with 3D printing as part of another project I’m working on. As part of that I’ve put together this Trangia fuel bottle adaptor that has come out really well.
If you want to print your own the .stl file can be downloaded from https://www.thingiverse.com/thing:3702293
NB – you dont necessarily need your own 3D printer. I’m using one that my local library has https://www.sutherlandshire.nsw.gov.au/Community/Library/Services/MakerSpace