And Paul was indeed right. These are 28mm Japanese type 92 tankettes, belonging to Ryan (who is a bit of a Japanese army nut!) from our club. And they are 3D printed (in, I think, SLA resin) by Trenchworx. I was quite stunned by how good they looked when Ryan showed them to me, hence grabbing a picture to share with my readers.
Trenchworx seem to use the 3D printer as a prototyping tool now: their main range is resin-cast once they've got a working model. Does mean the 3D stuff is pricey - the type 92s are $33 a go, for instance.
Also, they make a really nice Rolls Royce armoured car in resin, as part of their (Kickstartered) WW1 range, which I'm VERY tempted by for my Home Guard.