Firstly, thanks to Dave for letting me join.
We are in Sydney, Australia.
Here are a couple of photos of the garden fence line we had in 1999:


Since then we have mainly worked in 7 1/4″ gauge but the recent arrival of a grandchild and gift of a 3D printer got me going in O-gauge again.
This is my first public 3D design, it includes adapters to connect Big Big track to other systems: https://www.thingiverse.com/thing:5024058
Next came replacement couplers:

Tom