I located some 1.5mm diameter magnets which are almost the size of the spring supports on Belgravia. So, in 7mm scale, at least, this allows me to continue modelling some earlier locos as 3D printed resin offerings.
Still working on completing a selection to bring to the AGM.
This, the latest version of the Dapol Terrier, put alongside to check buffer heights etc. I still can't get my head around how small a Terrier is!